Merge #4090

4090: Diff indexing r=ManyTheFish a=ManyTheFish

This pull request aims to reduce the indexing time by computing a difference between the data added to the index and the data removed from the index before writing in LMDB.

## Why focus on reducing the writings in LMDB?

The indexing in Meilisearch is split into 3 main phases:
1) The computing or the extraction of the data (Multi-threaded)
2) The writing of the data in LMDB (Mono-threaded)
3) The processing of the prefix databases (Mono-threaded)

see below:
![Capture d’écran 2023-09-28 à 20 01 45](https://github.com/meilisearch/meilisearch/assets/6482087/51513162-7c39-4244-978b-2c6b60c43a56)


Because the writing is mono-threaded, it represents a bottleneck in the indexing, reducing the number of writes in LMDB will reduce the pressure on the main thread and should reduce the global time spent on the indexing.

## Give Feedback

We created [a dedicated discussion](https://github.com/meilisearch/meilisearch/discussions/4196) for users to try this new feature and to give feedback on bugs or performance issues.

## Technical approach
### Part 1: merge the addition and the deletion process
This part:
a) Aims to reduce the time spent on indexing only the filterable/sortable fields of documents, for example:
  - Updating the number of "likes" or "stars" of a song or a movie
  - Updating the "stock count" or the "price" of a product

b) Aims to reduce the time spent on writing in LMDB which should reduce the global indexing time for the highly multi-threaded machines by reducing the writing bottleneck.

c) Aims to reduce the average time spent to delete documents without having to keep the soft-deleted documents implementation

- [x] Create a preprocessing function that creates the diff-based documents chuck (`OBKV<fid, OBKV<AddDel, value>>`)
  - [x] and clearly separate the faceted fields and the searchable fields in two different chunks
- Change the parameters of the input extractor by taking an `OBKV<fid, OBKV<AddDel, value>>` instead of  `OBKV<fid, value>`.
  - [x] extract_docid_word_positions
  - [x] extract_geo_points
  - [x] extract_vector_points
  - [x] extract_fid_docid_facet_values
- Adapt the searchable extractors to the new diff-chucks
  - [x] extract_fid_word_count_docids
  - [x] extract_word_pair_proximity_docids
  - [x] extract_word_position_docids
  - [x] extract_word_docids
- Adapt the facet extractors to the new diff-chucks
  - [x] extract_facet_number_docids
  - [x] extract_facet_string_docids
  - [x] extract_fid_docid_facet_values
  - [x] FacetsUpdate
- [x] Adapt the prefix database extractors ⚠️ ⚠️ 
- [x] Make the LMDB writer remove the document_ids to delete at the same time the new document_ids are added
- [x] Remove document deletion pipeline
  - [x] remove `new_documents_ids` entirely and `replaced_documents_ids`
  - [x] reuse extracted external id from transform instead of re-extracting in `TypedChunks::Documents`
  - [x] Remove deletion pipeline after autobatcher
  - [x] remove autobatcher deletion pipeline
    - [x] everything uses `IndexOperation::DocumentOperation`
    - [x] repair deletion by internal id for filter by delete
    - [x] Improve the deletion via internal ids by avoiding iterating over the whole set of external document ids.  
- [x] Remove soft-deleted documents

#### FIXME

- [x] field distribution is not correctly updated after deletion
- [x] missing documents in the tests of tokenizer_customization

### Part 2: Only compute the documents field by field
This part aims to reduce the global indexing time for any kind of partial document modification on any size of machine from the mono-threaded one to the highly multi-threaded one.

- [ ] Make the preprocessing function only send the fields that changed to the extractors
- [ ] remove the `word_docids` and `exact_word_docids` database and adapt the search (⚠️ could impact the search performances)
- [ ] replace the `word_pair_proximity_docids` database with a `word_pair_proximity_fid_docids` database and adapt the search (⚠️ could impact the search performances)
- [ ] Adapt the prefix database extractors ⚠️ ⚠️

## Technical Concerns
- The part 1 implementation could increase the indexing time for the smallest machines (with few threads) by increasing the extracting time (multi-threaded) more than the writing time (mono-threaded)
- The part 2 implementation needs to change the databases which could have a significant impact on the search performances
- The prefix databases are a bit special to process and may be a pain to adapt to the difference-based indexing

Co-authored-by: ManyTheFish <many@meilisearch.com>
Co-authored-by: Clément Renault <clement@meilisearch.com>
Co-authored-by: Louis Dureuil <louis@meilisearch.com>

Cargo.lock

@@ -1663,12 +1663,13 @@ checksum = "d2fabcfbdc87f4758337ca535fb41a6d701b65693ce38287d856d1674551ec9b"
 
 [[package]]
 name = "grenad"
-version = "0.4.4"
+version = "0.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5232b2d157b7bf63d7abe1b12177039e58db2f29e377517c0cdee1578cca4c93"
+checksum = "6a007932af5475ebb5c63bef8812bb1c36f317983bb4ca663e9d6dd58d6a0f8c"
 dependencies = [
  "bytemuck",
  "byteorder",
+ "rayon",
  "tempfile",
 ]
 
@@ -2703,6 +2704,7 @@ dependencies = [
  "logging_timer",
  "maplit",
  "md5",
+ "meili-snap",
  "memmap2",
  "mimalloc",
  "obkv",
@@ -2865,9 +2867,9 @@ dependencies = [
 
 [[package]]
 name = "obkv"
-version = "0.2.0"
+version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f69e48cd7c8e5bb52a1da1287fdbfd877c32673176583ce664cd63b201aba385"
+checksum = "6c459142426056c639ff88d053ebaaaeca0ee1411c94362892398ef4ccd81080"
 
 [[package]]
 name = "once_cell"

benchmarks/benches/indexing.rs

@@ -6,9 +6,7 @@ use std::path::Path;
 
 use criterion::{criterion_group, criterion_main, Criterion};
 use milli::heed::{EnvOpenOptions, RwTxn};
-use milli::update::{
+use milli::update::{IndexDocuments, IndexDocumentsConfig, IndexerConfig, Settings};
-    DeleteDocuments, IndexDocuments, IndexDocumentsConfig, IndexerConfig, Settings,
-};
 use milli::Index;
 use rand::seq::SliceRandom;
 use rand_chacha::rand_core::SeedableRng;
@@ -266,17 +264,7 @@ fn deleting_songs_in_batches_default(c: &mut Criterion) {
                 (index, document_ids_to_delete)
             },
             move |(index, document_ids_to_delete)| {
-                let mut wtxn = index.write_txn().unwrap();
+                delete_documents_from_ids(index, document_ids_to_delete)
-
-                for ids in document_ids_to_delete {
-                    let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-                    builder.delete_documents(&ids);
-                    builder.execute().unwrap();
-                }
-
-                wtxn.commit().unwrap();
-
-                index.prepare_for_closing().wait();
             },
         )
     });
@@ -613,17 +601,7 @@ fn deleting_wiki_in_batches_default(c: &mut Criterion) {
                 (index, document_ids_to_delete)
             },
             move |(index, document_ids_to_delete)| {
-                let mut wtxn = index.write_txn().unwrap();
+                delete_documents_from_ids(index, document_ids_to_delete)
-
-                for ids in document_ids_to_delete {
-                    let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-                    builder.delete_documents(&ids);
-                    builder.execute().unwrap();
-                }
-
-                wtxn.commit().unwrap();
-
-                index.prepare_for_closing().wait();
             },
         )
     });
@@ -875,22 +853,31 @@ fn deleting_movies_in_batches_default(c: &mut Criterion) {
                 (index, document_ids_to_delete)
             },
             move |(index, document_ids_to_delete)| {
-                let mut wtxn = index.write_txn().unwrap();
+                delete_documents_from_ids(index, document_ids_to_delete)
-
-                for ids in document_ids_to_delete {
-                    let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-                    builder.delete_documents(&ids);
-                    builder.execute().unwrap();
-                }
-
-                wtxn.commit().unwrap();
-
-                index.prepare_for_closing().wait();
             },
         )
     });
 }
 
+fn delete_documents_from_ids(index: Index, document_ids_to_delete: Vec<RoaringBitmap>) {
+    let mut wtxn = index.write_txn().unwrap();
+
+    let indexer_config = IndexerConfig::default();
+    for ids in document_ids_to_delete {
+        let config = IndexDocumentsConfig::default();
+
+        let mut builder =
+            IndexDocuments::new(&mut wtxn, &index, &indexer_config, config, |_| (), || false)
+                .unwrap();
+        (builder, _) = builder.remove_documents_from_db_no_batch(&ids).unwrap();
+        builder.execute().unwrap();
+    }
+
+    wtxn.commit().unwrap();
+
+    index.prepare_for_closing().wait();
+}
+
 fn indexing_movies_in_three_batches(c: &mut Criterion) {
     let mut group = c.benchmark_group("indexing");
     group.sample_size(BENCHMARK_ITERATION);
@@ -1112,17 +1099,7 @@ fn deleting_nested_movies_in_batches_default(c: &mut Criterion) {
                 (index, document_ids_to_delete)
             },
             move |(index, document_ids_to_delete)| {
-                let mut wtxn = index.write_txn().unwrap();
+                delete_documents_from_ids(index, document_ids_to_delete)
-
-                for ids in document_ids_to_delete {
-                    let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-                    builder.delete_documents(&ids);
-                    builder.execute().unwrap();
-                }
-
-                wtxn.commit().unwrap();
-
-                index.prepare_for_closing().wait();
             },
         )
     });
@@ -1338,17 +1315,7 @@ fn deleting_geo_in_batches_default(c: &mut Criterion) {
                 (index, document_ids_to_delete)
             },
             move |(index, document_ids_to_delete)| {
-                let mut wtxn = index.write_txn().unwrap();
+                delete_documents_from_ids(index, document_ids_to_delete)
-
-                for ids in document_ids_to_delete {
-                    let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-                    builder.delete_documents(&ids);
-                    builder.execute().unwrap();
-                }
-
-                wtxn.commit().unwrap();
-
-                index.prepare_for_closing().wait();
             },
         )
     });

dump/src/reader/snapshots/dump__reader__test__import_dump_v1-11.snap

@@ -1,24 +0,0 @@
----
-source: dump/src/reader/mod.rs
-expression: spells.settings().unwrap()
----
-{
-  "displayedAttributes": [
-    "*"
-  ],
-  "searchableAttributes": [
-    "*"
-  ],
-  "filterableAttributes": [],
-  "sortableAttributes": [],
-  "rankingRules": [
-    "typo",
-    "words",
-    "proximity",
-    "attribute",
-    "exactness"
-  ],
-  "stopWords": [],
-  "synonyms": {},
-  "distinctAttribute": null
-}

dump/src/reader/snapshots/dump__reader__test__import_dump_v1-5.snap

@@ -1,38 +0,0 @@
----
-source: dump/src/reader/mod.rs
-expression: products.settings().unwrap()
----
-{
-  "displayedAttributes": [
-    "*"
-  ],
-  "searchableAttributes": [
-    "*"
-  ],
-  "filterableAttributes": [],
-  "sortableAttributes": [],
-  "rankingRules": [
-    "typo",
-    "words",
-    "proximity",
-    "attribute",
-    "exactness"
-  ],
-  "stopWords": [],
-  "synonyms": {
-    "android": [
-      "phone",
-      "smartphone"
-    ],
-    "iphone": [
-      "phone",
-      "smartphone"
-    ],
-    "phone": [
-      "android",
-      "iphone",
-      "smartphone"
-    ]
-  },
-  "distinctAttribute": null
-}

dump/src/reader/snapshots/dump__reader__test__import_dump_v1-8.snap

@@ -1,31 +0,0 @@
----
-source: dump/src/reader/mod.rs
-expression: movies.settings().unwrap()
----
-{
-  "displayedAttributes": [
-    "*"
-  ],
-  "searchableAttributes": [
-    "*"
-  ],
-  "filterableAttributes": [
-    "genres",
-    "id"
-  ],
-  "sortableAttributes": [
-    "genres",
-    "id"
-  ],
-  "rankingRules": [
-    "typo",
-    "words",
-    "proximity",
-    "attribute",
-    "exactness",
-    "release_date:asc"
-  ],
-  "stopWords": [],
-  "synonyms": {},
-  "distinctAttribute": null
-}

index-scheduler/src/batch.rs

@@ -24,14 +24,13 @@ use std::fs::{self, File};
 use std::io::BufWriter;
 
 use dump::IndexMetadata;
-use log::{debug, error, info};
+use log::{debug, error, info, trace};
 use meilisearch_types::error::Code;
 use meilisearch_types::heed::{RoTxn, RwTxn};
 use meilisearch_types::milli::documents::{obkv_to_object, DocumentsBatchReader};
 use meilisearch_types::milli::heed::CompactionOption;
 use meilisearch_types::milli::update::{
-    DeleteDocuments, DocumentDeletionResult, IndexDocumentsConfig, IndexDocumentsMethod,
+    IndexDocumentsConfig, IndexDocumentsMethod, IndexerConfig, Settings as MilliSettings,
-    Settings as MilliSettings,
 };
 use meilisearch_types::milli::{self, Filter, BEU32};
 use meilisearch_types::settings::{apply_settings_to_builder, Settings, Unchecked};
@@ -44,7 +43,7 @@ use uuid::Uuid;
 
 use crate::autobatcher::{self, BatchKind};
 use crate::utils::{self, swap_index_uid_in_task};
-use crate::{Error, IndexScheduler, ProcessingTasks, Result, TaskId};
+use crate::{Error, IndexScheduler, MustStopProcessing, ProcessingTasks, Result, TaskId};
 
 /// Represents a combination of tasks that can all be processed at the same time.
 ///
@@ -105,12 +104,6 @@ pub(crate) enum IndexOperation {
         operations: Vec<DocumentOperation>,
         tasks: Vec<Task>,
     },
-    DocumentDeletion {
-        index_uid: String,
-        // The vec associated with each document deletion tasks.
-        documents: Vec<Vec<String>>,
-        tasks: Vec<Task>,
-    },
     IndexDocumentDeletionByFilter {
         index_uid: String,
         task: Task,
@@ -162,7 +155,6 @@ impl Batch {
             }
             Batch::IndexOperation { op, .. } => match op {
                 IndexOperation::DocumentOperation { tasks, .. }
-                | IndexOperation::DocumentDeletion { tasks, .. }
                 | IndexOperation::Settings { tasks, .. }
                 | IndexOperation::DocumentClear { tasks, .. } => {
                     tasks.iter().map(|task| task.uid).collect()
@@ -227,7 +219,6 @@ impl IndexOperation {
     pub fn index_uid(&self) -> &str {
         match self {
             IndexOperation::DocumentOperation { index_uid, .. }
-            | IndexOperation::DocumentDeletion { index_uid, .. }
             | IndexOperation::IndexDocumentDeletionByFilter { index_uid, .. }
             | IndexOperation::DocumentClear { index_uid, .. }
             | IndexOperation::Settings { index_uid, .. }
@@ -243,9 +234,6 @@ impl fmt::Display for IndexOperation {
             IndexOperation::DocumentOperation { .. } => {
                 f.write_str("IndexOperation::DocumentOperation")
             }
-            IndexOperation::DocumentDeletion { .. } => {
-                f.write_str("IndexOperation::DocumentDeletion")
-            }
             IndexOperation::IndexDocumentDeletionByFilter { .. } => {
                 f.write_str("IndexOperation::IndexDocumentDeletionByFilter")
             }
@@ -348,18 +336,27 @@ impl IndexScheduler {
             BatchKind::DocumentDeletion { deletion_ids } => {
                 let tasks = self.get_existing_tasks(rtxn, deletion_ids)?;
 
-                let mut documents = Vec::new();
+                let mut operations = Vec::with_capacity(tasks.len());
+                let mut documents_counts = Vec::with_capacity(tasks.len());
                 for task in &tasks {
                     match task.kind {
                         KindWithContent::DocumentDeletion { ref documents_ids, .. } => {
-                            documents.push(documents_ids.clone())
+                            operations.push(DocumentOperation::Delete(documents_ids.clone()));
+                            documents_counts.push(documents_ids.len() as u64);
                         }
                         _ => unreachable!(),
                     }
                 }
 
                 Ok(Some(Batch::IndexOperation {
-                    op: IndexOperation::DocumentDeletion { index_uid, documents, tasks },
+                    op: IndexOperation::DocumentOperation {
+                        index_uid,
+                        primary_key: None,
+                        method: IndexDocumentsMethod::ReplaceDocuments,
+                        documents_counts,
+                        operations,
+                        tasks,
+                    },
                     must_create_index,
                 }))
             }
@@ -1204,7 +1201,7 @@ impl IndexScheduler {
                     index,
                     indexer_config,
                     config,
-                    |indexing_step| debug!("update: {:?}", indexing_step),
+                    |indexing_step| trace!("update: {:?}", indexing_step),
                     || must_stop_processing.get(),
                 )?;
 
@@ -1251,7 +1248,8 @@ impl IndexScheduler {
                             let (new_builder, user_result) =
                                 builder.remove_documents(document_ids)?;
                             builder = new_builder;
-
+                            // Uses Invariant: remove documents actually always returns Ok for the inner result
+                            let count = user_result.unwrap();
                             let provided_ids =
                                 if let Some(Details::DocumentDeletion { provided_ids, .. }) =
                                     task.details
@@ -1262,23 +1260,11 @@ impl IndexScheduler {
                                     unreachable!();
                                 };
 
-                            match user_result {
+                            task.status = Status::Succeeded;
-                                Ok(count) => {
+                            task.details = Some(Details::DocumentDeletion {
-                                    task.status = Status::Succeeded;
+                                provided_ids,
-                                    task.details = Some(Details::DocumentDeletion {
+                                deleted_documents: Some(count),
-                                        provided_ids,
+                            });
-                                        deleted_documents: Some(count),
-                                    });
-                                }
-                                Err(e) => {
-                                    task.status = Status::Failed;
-                                    task.details = Some(Details::DocumentDeletion {
-                                        provided_ids,
-                                        deleted_documents: Some(0),
-                                    });
-                                    task.error = Some(milli::Error::from(e).into());
-                                }
-                            }
                         }
                     }
                 }
@@ -1293,31 +1279,13 @@ impl IndexScheduler {
                         milli::update::Settings::new(index_wtxn, index, indexer_config);
                     builder.reset_primary_key();
                     builder.execute(
-                        |indexing_step| debug!("update: {:?}", indexing_step),
+                        |indexing_step| trace!("update: {:?}", indexing_step),
                         || must_stop_processing.clone().get(),
                     )?;
                 }
 
                 Ok(tasks)
             }
-            IndexOperation::DocumentDeletion { index_uid: _, documents, mut tasks } => {
-                let mut builder = milli::update::DeleteDocuments::new(index_wtxn, index)?;
-                documents.iter().flatten().for_each(|id| {
-                    builder.delete_external_id(id);
-                });
-
-                let DocumentDeletionResult { deleted_documents, .. } = builder.execute()?;
-
-                for (task, documents) in tasks.iter_mut().zip(documents) {
-                    task.status = Status::Succeeded;
-                    task.details = Some(Details::DocumentDeletion {
-                        provided_ids: documents.len(),
-                        deleted_documents: Some(deleted_documents.min(documents.len() as u64)),
-                    });
-                }
-
-                Ok(tasks)
-            }
             IndexOperation::IndexDocumentDeletionByFilter { mut task, index_uid: _ } => {
                 let filter =
                     if let KindWithContent::DocumentDeletionByFilter { filter_expr, .. } =
@@ -1327,7 +1295,13 @@ impl IndexScheduler {
                     } else {
                         unreachable!()
                     };
-                let deleted_documents = delete_document_by_filter(index_wtxn, filter, index);
+                let deleted_documents = delete_document_by_filter(
+                    index_wtxn,
+                    filter,
+                    self.index_mapper.indexer_config(),
+                    self.must_stop_processing.clone(),
+                    index,
+                );
                 let original_filter = if let Some(Details::DocumentDeletionByFilter {
                     original_filter,
                     deleted_documents: _,
@@ -1561,6 +1535,8 @@ impl IndexScheduler {
 fn delete_document_by_filter<'a>(
     wtxn: &mut RwTxn<'a, '_>,
     filter: &serde_json::Value,
+    indexer_config: &IndexerConfig,
+    must_stop_processing: MustStopProcessing,
     index: &'a Index,
 ) -> Result<u64> {
     let filter = Filter::from_json(filter)?;
@@ -1571,9 +1547,26 @@ fn delete_document_by_filter<'a>(
             }
             e => e.into(),
         })?;
-        let mut delete_operation = DeleteDocuments::new(wtxn, index)?;
+
-        delete_operation.delete_documents(&candidates);
+        let config = IndexDocumentsConfig {
-        delete_operation.execute().map(|result| result.deleted_documents)?
+            update_method: IndexDocumentsMethod::ReplaceDocuments,
+            ..Default::default()
+        };
+
+        let mut builder = milli::update::IndexDocuments::new(
+            wtxn,
+            index,
+            indexer_config,
+            config,
+            |indexing_step| debug!("update: {:?}", indexing_step),
+            || must_stop_processing.get(),
+        )?;
+
+        let (new_builder, count) = builder.remove_documents_from_db_no_batch(&candidates)?;
+        builder = new_builder;
+
+        let _ = builder.execute()?;
+        count
     } else {
         0
     })

meilisearch-types/src/error.rs

@@ -324,7 +324,6 @@ impl ErrorCode for milli::Error {
                     UserError::SerdeJson(_)
                     | UserError::InvalidLmdbOpenOptions
                     | UserError::DocumentLimitReached
-                    | UserError::AccessingSoftDeletedDocument { .. }
                     | UserError::UnknownInternalDocumentId { .. } => Code::Internal,
                     UserError::InvalidStoreFile => Code::InvalidStoreFile,
                     UserError::NoSpaceLeftOnDevice => Code::NoSpaceLeftOnDevice,

meilisearch/src/lib.rs

@@ -362,7 +362,7 @@ fn import_dump(
                 update_method: IndexDocumentsMethod::ReplaceDocuments,
                 ..Default::default()
             },
-            |indexing_step| log::debug!("update: {:?}", indexing_step),
+            |indexing_step| log::trace!("update: {:?}", indexing_step),
             || false,
         )?;
 

meilisearch/src/routes/indexes/documents.rs

@@ -612,8 +612,8 @@ fn retrieve_document<S: AsRef<str>>(
     let all_fields: Vec<_> = fields_ids_map.iter().map(|(id, _)| id).collect();
 
     let internal_id = index
-        .external_documents_ids(&txn)?
+        .external_documents_ids()
-        .get(doc_id.as_bytes())
+        .get(&txn, doc_id)?
         .ok_or_else(|| MeilisearchHttpError::DocumentNotFound(doc_id.to_string()))?;
 
     let document = index

meilisearch/tests/documents/delete_documents.rs

@@ -397,7 +397,7 @@ async fn delete_document_by_complex_filter() {
       "canceledBy": null,
       "details": {
         "providedIds": 0,
-        "deletedDocuments": 4,
+        "deletedDocuments": 2,
         "originalFilter": "[[\"color = green\",\"color NOT EXISTS\"]]"
       },
       "error": null,

milli/Cargo.toml

@@ -26,8 +26,8 @@ flatten-serde-json = { path = "../flatten-serde-json" }
 fst = "0.4.7"
 fxhash = "0.2.1"
 geoutils = "0.5.1"
-grenad = { version = "0.4.4", default-features = false, features = [
+grenad = { version = "0.4.5", default-features = false, features = [
-    "tempfile",
+    "rayon", "tempfile"
 ] }
 heed = { git = "https://github.com/meilisearch/heed", tag = "v0.12.7", default-features = false, features = [
     "lmdb", "read-txn-no-tls"
@@ -79,6 +79,7 @@ big_s = "1.0.2"
 insta = "1.29.0"
 maplit = "1.0.2"
 md5 = "0.7.0"
+meili-snap = { path = "../meili-snap" }
 rand = { version = "0.8.5", features = ["small_rng"] }
 
 [features]

milli/src/documents/mod.rs

@@ -1,5 +1,6 @@
 mod builder;
 mod enriched;
+mod primary_key;
 mod reader;
 mod serde_impl;
 
@@ -11,6 +12,7 @@ use bimap::BiHashMap;
 pub use builder::DocumentsBatchBuilder;
 pub use enriched::{EnrichedDocument, EnrichedDocumentsBatchCursor, EnrichedDocumentsBatchReader};
 use obkv::KvReader;
+pub use primary_key::{DocumentIdExtractionError, FieldIdMapper, PrimaryKey, DEFAULT_PRIMARY_KEY};
 pub use reader::{DocumentsBatchCursor, DocumentsBatchCursorError, DocumentsBatchReader};
 use serde::{Deserialize, Serialize};
 
@@ -87,6 +89,12 @@ impl DocumentsBatchIndex {
     }
 }
 
+impl FieldIdMapper for DocumentsBatchIndex {
+    fn id(&self, name: &str) -> Option<FieldId> {
+        self.id(name)
+    }
+}
+
 #[derive(Debug, thiserror::Error)]
 pub enum Error {
     #[error("Error parsing number {value:?} at line {line}: {error}")]

milli/src/documents/primary_key.rs

@@ -0,0 +1,172 @@
+use std::iter;
+use std::result::Result as StdResult;
+
+use serde_json::Value;
+
+use crate::{FieldId, InternalError, Object, Result, UserError};
+
+/// The symbol used to define levels in a nested primary key.
+const PRIMARY_KEY_SPLIT_SYMBOL: char = '.';
+
+/// The default primary that is used when not specified.
+pub const DEFAULT_PRIMARY_KEY: &str = "id";
+
+/// Trait for objects that can map the name of a field to its [`FieldId`].
+pub trait FieldIdMapper {
+    /// Attempts to map the passed name to its [`FieldId`].
+    ///
+    /// `None` if the field with this name was not found.
+    fn id(&self, name: &str) -> Option<FieldId>;
+}
+
+/// A type that represent the type of primary key that has been set
+/// for this index, a classic flat one or a nested one.
+#[derive(Debug, Clone, Copy)]
+pub enum PrimaryKey<'a> {
+    Flat { name: &'a str, field_id: FieldId },
+    Nested { name: &'a str },
+}
+
+pub enum DocumentIdExtractionError {
+    InvalidDocumentId(UserError),
+    MissingDocumentId,
+    TooManyDocumentIds(usize),
+}
+
+impl<'a> PrimaryKey<'a> {
+    pub fn new(path: &'a str, fields: &impl FieldIdMapper) -> Option<Self> {
+        Some(if path.contains(PRIMARY_KEY_SPLIT_SYMBOL) {
+            Self::Nested { name: path }
+        } else {
+            let field_id = fields.id(path)?;
+            Self::Flat { name: path, field_id }
+        })
+    }
+
+    pub fn name(&self) -> &str {
+        match self {
+            PrimaryKey::Flat { name, .. } => name,
+            PrimaryKey::Nested { name } => name,
+        }
+    }
+
+    pub fn document_id(
+        &self,
+        document: &obkv::KvReader<FieldId>,
+        fields: &impl FieldIdMapper,
+    ) -> Result<StdResult<String, DocumentIdExtractionError>> {
+        match self {
+            PrimaryKey::Flat { name: _, field_id } => match document.get(*field_id) {
+                Some(document_id_bytes) => {
+                    let document_id = serde_json::from_slice(document_id_bytes)
+                        .map_err(InternalError::SerdeJson)?;
+                    match validate_document_id_value(document_id)? {
+                        Ok(document_id) => Ok(Ok(document_id)),
+                        Err(user_error) => {
+                            Ok(Err(DocumentIdExtractionError::InvalidDocumentId(user_error)))
+                        }
+                    }
+                }
+                None => Ok(Err(DocumentIdExtractionError::MissingDocumentId)),
+            },
+            nested @ PrimaryKey::Nested { .. } => {
+                let mut matching_documents_ids = Vec::new();
+                for (first_level_name, right) in nested.possible_level_names() {
+                    if let Some(field_id) = fields.id(first_level_name) {
+                        if let Some(value_bytes) = document.get(field_id) {
+                            let object = serde_json::from_slice(value_bytes)
+                                .map_err(InternalError::SerdeJson)?;
+                            fetch_matching_values(object, right, &mut matching_documents_ids);
+
+                            if matching_documents_ids.len() >= 2 {
+                                return Ok(Err(DocumentIdExtractionError::TooManyDocumentIds(
+                                    matching_documents_ids.len(),
+                                )));
+                            }
+                        }
+                    }
+                }
+
+                match matching_documents_ids.pop() {
+                    Some(document_id) => match validate_document_id_value(document_id)? {
+                        Ok(document_id) => Ok(Ok(document_id)),
+                        Err(user_error) => {
+                            Ok(Err(DocumentIdExtractionError::InvalidDocumentId(user_error)))
+                        }
+                    },
+                    None => Ok(Err(DocumentIdExtractionError::MissingDocumentId)),
+                }
+            }
+        }
+    }
+
+    /// Returns an `Iterator` that gives all the possible fields names the primary key
+    /// can have depending of the first level name and depth of the objects.
+    pub fn possible_level_names(&self) -> impl Iterator<Item = (&str, &str)> + '_ {
+        let name = self.name();
+        name.match_indices(PRIMARY_KEY_SPLIT_SYMBOL)
+            .map(move |(i, _)| (&name[..i], &name[i + PRIMARY_KEY_SPLIT_SYMBOL.len_utf8()..]))
+            .chain(iter::once((name, "")))
+    }
+}
+
+fn fetch_matching_values(value: Value, selector: &str, output: &mut Vec<Value>) {
+    match value {
+        Value::Object(object) => fetch_matching_values_in_object(object, selector, "", output),
+        otherwise => output.push(otherwise),
+    }
+}
+
+fn fetch_matching_values_in_object(
+    object: Object,
+    selector: &str,
+    base_key: &str,
+    output: &mut Vec<Value>,
+) {
+    for (key, value) in object {
+        let base_key = if base_key.is_empty() {
+            key.to_string()
+        } else {
+            format!("{}{}{}", base_key, PRIMARY_KEY_SPLIT_SYMBOL, key)
+        };
+
+        if starts_with(selector, &base_key) {
+            match value {
+                Value::Object(object) => {
+                    fetch_matching_values_in_object(object, selector, &base_key, output)
+                }
+                value => output.push(value),
+            }
+        }
+    }
+}
+
+fn starts_with(selector: &str, key: &str) -> bool {
+    selector.strip_prefix(key).map_or(false, |tail| {
+        tail.chars().next().map(|c| c == PRIMARY_KEY_SPLIT_SYMBOL).unwrap_or(true)
+    })
+}
+
+// FIXME: move to a DocumentId struct
+
+fn validate_document_id(document_id: &str) -> Option<&str> {
+    if !document_id.is_empty()
+        && document_id.chars().all(|c| matches!(c, 'a'..='z' | 'A'..='Z' | '0'..='9' | '-' | '_'))
+    {
+        Some(document_id)
+    } else {
+        None
+    }
+}
+
+pub fn validate_document_id_value(document_id: Value) -> Result<StdResult<String, UserError>> {
+    match document_id {
+        Value::String(string) => match validate_document_id(&string) {
+            Some(s) if s.len() == string.len() => Ok(Ok(string)),
+            Some(s) => Ok(Ok(s.to_string())),
+            None => Ok(Err(UserError::InvalidDocumentId { document_id: Value::String(string) })),
+        },
+        Value::Number(number) if number.is_i64() => Ok(Ok(number.to_string())),
+        content => Ok(Err(UserError::InvalidDocumentId { document_id: content })),
+    }
+}

milli/src/error.rs

@@ -89,8 +89,6 @@ pub enum FieldIdMapMissingEntry {
 
 #[derive(Error, Debug)]
 pub enum UserError {
-    #[error("A soft deleted internal document id have been used: `{document_id}`.")]
-    AccessingSoftDeletedDocument { document_id: DocumentId },
     #[error("A document cannot contain more than 65,535 fields.")]
     AttributeLimitReached,
     #[error(transparent)]

milli/src/external_documents_ids.rs

@@ -1,159 +1,75 @@
-use std::borrow::Cow;
 use std::collections::HashMap;
-use std::convert::TryInto;
-use std::{fmt, str};
 
-use fst::map::IndexedValue;
+use heed::types::{OwnedType, Str};
-use fst::{IntoStreamer, Streamer};
+use heed::{Database, RoIter, RoTxn, RwTxn};
-use roaring::RoaringBitmap;
 
-const DELETED_ID: u64 = u64::MAX;
+use crate::{DocumentId, BEU32};
 
-pub struct ExternalDocumentsIds<'a> {
+pub enum DocumentOperationKind {
-    pub(crate) hard: fst::Map<Cow<'a, [u8]>>,
+    Create,
-    pub(crate) soft: fst::Map<Cow<'a, [u8]>>,
+    Delete,
-    soft_deleted_docids: RoaringBitmap,
 }
 
-impl<'a> ExternalDocumentsIds<'a> {
+pub struct DocumentOperation {
-    pub fn new(
+    pub external_id: String,
-        hard: fst::Map<Cow<'a, [u8]>>,
+    pub internal_id: DocumentId,
-        soft: fst::Map<Cow<'a, [u8]>>,
+    pub kind: DocumentOperationKind,
-        soft_deleted_docids: RoaringBitmap,
+}
-    ) -> ExternalDocumentsIds<'a> {
-        ExternalDocumentsIds { hard, soft, soft_deleted_docids }
-    }
 
-    pub fn into_static(self) -> ExternalDocumentsIds<'static> {
+pub struct ExternalDocumentsIds(Database<Str, OwnedType<BEU32>>);
-        ExternalDocumentsIds {
+
-            hard: self.hard.map_data(|c| Cow::Owned(c.into_owned())).unwrap(),
+impl ExternalDocumentsIds {
-            soft: self.soft.map_data(|c| Cow::Owned(c.into_owned())).unwrap(),
+    pub fn new(db: Database<Str, OwnedType<BEU32>>) -> ExternalDocumentsIds {
-            soft_deleted_docids: self.soft_deleted_docids,
+        ExternalDocumentsIds(db)
-        }
     }
 
     /// Returns `true` if hard and soft external documents lists are empty.
-    pub fn is_empty(&self) -> bool {
+    pub fn is_empty(&self, rtxn: &RoTxn) -> heed::Result<bool> {
-        self.hard.is_empty() && self.soft.is_empty()
+        self.0.is_empty(rtxn).map_err(Into::into)
     }
 
-    pub fn get<A: AsRef<[u8]>>(&self, external_id: A) -> Option<u32> {
+    pub fn get<A: AsRef<str>>(&self, rtxn: &RoTxn, external_id: A) -> heed::Result<Option<u32>> {
-        let external_id = external_id.as_ref();
+        Ok(self.0.get(rtxn, external_id.as_ref())?.map(|x| x.get()))
-        match self.soft.get(external_id).or_else(|| self.hard.get(external_id)) {
-            Some(id) if id != DELETED_ID && !self.soft_deleted_docids.contains(id as u32) => {
-                Some(id.try_into().unwrap())
-            }
-            _otherwise => None,
-        }
-    }
-
-    /// Rebuild the internal FSTs in the ExternalDocumentsIds structure such that they
-    /// don't contain any soft deleted document id.
-    pub fn delete_soft_deleted_documents_ids_from_fsts(&mut self) -> fst::Result<()> {
-        let mut new_hard_builder = fst::MapBuilder::memory();
-
-        let union_op = self.hard.op().add(&self.soft).r#union();
-        let mut iter = union_op.into_stream();
-        while let Some((external_id, docids)) = iter.next() {
-            // prefer selecting the ids from soft, always
-            let id = indexed_last_value(docids).unwrap();
-            if id != DELETED_ID && !self.soft_deleted_docids.contains(id as u32) {
-                new_hard_builder.insert(external_id, id)?;
-            }
-        }
-        drop(iter);
-
-        // Delete soft map completely
-        self.soft = fst::Map::default().map_data(Cow::Owned)?;
-        // We save the new map as the new hard map.
-        self.hard = new_hard_builder.into_map().map_data(Cow::Owned)?;
-
-        Ok(())
-    }
-
-    pub fn insert_ids<A: AsRef<[u8]>>(&mut self, other: &fst::Map<A>) -> fst::Result<()> {
-        let union_op = self.soft.op().add(other).r#union();
-
-        let mut new_soft_builder = fst::MapBuilder::memory();
-        let mut iter = union_op.into_stream();
-        while let Some((external_id, marked_docids)) = iter.next() {
-            let id = indexed_last_value(marked_docids).unwrap();
-            new_soft_builder.insert(external_id, id)?;
-        }
-
-        drop(iter);
-
-        // We save the new map as the new soft map.
-        self.soft = new_soft_builder.into_map().map_data(Cow::Owned)?;
-        self.merge_soft_into_hard()
     }
 
     /// An helper function to debug this type, returns an `HashMap` of both,
     /// soft and hard fst maps, combined.
-    pub fn to_hash_map(&self) -> HashMap<String, u32> {
+    pub fn to_hash_map(&self, rtxn: &RoTxn) -> heed::Result<HashMap<String, u32>> {
-        let mut map = HashMap::new();
+        let mut map = HashMap::default();
-
+        for result in self.0.iter(rtxn)? {
-        let union_op = self.hard.op().add(&self.soft).r#union();
+            let (external, internal) = result?;
-        let mut iter = union_op.into_stream();
+            map.insert(external.to_owned(), internal.get());
-        while let Some((external_id, marked_docids)) = iter.next() {
-            let id = indexed_last_value(marked_docids).unwrap();
-            if id != DELETED_ID {
-                let external_id = str::from_utf8(external_id).unwrap();
-                map.insert(external_id.to_owned(), id.try_into().unwrap());
-            }
         }
-
+        Ok(map)
-        map
     }
 
-    /// Return an fst of the combined hard and soft deleted ID.
+    /// Applies the list of operations passed as argument, modifying the current external to internal id mapping.
-    pub fn to_fst<'b>(&'b self) -> fst::Result<Cow<'b, fst::Map<Cow<'a, [u8]>>>> {
+    ///
-        if self.soft.is_empty() {
+    /// If the list contains multiple operations on the same external id, then the result is unspecified.
-            return Ok(Cow::Borrowed(&self.hard));
+    ///
-        }
+    /// # Panics
-        let union_op = self.hard.op().add(&self.soft).r#union();
+    ///
-
+    /// - If attempting to delete a document that doesn't exist
-        let mut iter = union_op.into_stream();
+    /// - If attempting to create a document that already exists
-        let mut new_hard_builder = fst::MapBuilder::memory();
+    pub fn apply(&self, wtxn: &mut RwTxn, operations: Vec<DocumentOperation>) -> heed::Result<()> {
-        while let Some((external_id, marked_docids)) = iter.next() {
+        for DocumentOperation { external_id, internal_id, kind } in operations {
-            let value = indexed_last_value(marked_docids).unwrap();
+            match kind {
-            if value != DELETED_ID {
+                DocumentOperationKind::Create => {
-                new_hard_builder.insert(external_id, value)?;
+                    self.0.put(wtxn, &external_id, &BEU32::new(internal_id))?;
+                }
+                DocumentOperationKind::Delete => {
+                    if !self.0.delete(wtxn, &external_id)? {
+                        panic!("Attempting to delete a non-existing document")
+                    }
+                }
             }
         }
 
-        drop(iter);
-
-        Ok(Cow::Owned(new_hard_builder.into_map().map_data(Cow::Owned)?))
-    }
-
-    fn merge_soft_into_hard(&mut self) -> fst::Result<()> {
-        if self.soft.len() >= self.hard.len() / 2 {
-            self.hard = self.to_fst()?.into_owned();
-            self.soft = fst::Map::default().map_data(Cow::Owned)?;
-        }
-
         Ok(())
     }
-}
 
-impl fmt::Debug for ExternalDocumentsIds<'_> {
+    /// Returns an iterator over all the external ids.
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    pub fn iter<'t>(&self, rtxn: &'t RoTxn) -> heed::Result<RoIter<'t, Str, OwnedType<BEU32>>> {
-        f.debug_tuple("ExternalDocumentsIds").field(&self.to_hash_map()).finish()
+        self.0.iter(rtxn)
     }
 }
-
-impl Default for ExternalDocumentsIds<'static> {
-    fn default() -> Self {
-        ExternalDocumentsIds {
-            hard: fst::Map::default().map_data(Cow::Owned).unwrap(),
-            soft: fst::Map::default().map_data(Cow::Owned).unwrap(),
-            soft_deleted_docids: RoaringBitmap::new(),
-        }
-    }
-}
-
-/// Returns the value of the `IndexedValue` with the highest _index_.
-fn indexed_last_value(indexed_values: &[IndexedValue]) -> Option<u64> {
-    indexed_values.iter().copied().max_by_key(|iv| iv.index).map(|iv| iv.value)
-}

milli/src/fields_ids_map.rs

@@ -81,6 +81,12 @@ impl Default for FieldsIdsMap {
     }
 }
 
+impl crate::documents::FieldIdMapper for FieldsIdsMap {
+    fn id(&self, name: &str) -> Option<FieldId> {
+        self.id(name)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

milli/src/heed_codec/roaring_bitmap/cbo_roaring_bitmap_codec.rs

@@ -6,6 +6,7 @@ use byteorder::{NativeEndian, ReadBytesExt, WriteBytesExt};
 use roaring::RoaringBitmap;
 
 use crate::heed_codec::BytesDecodeOwned;
+use crate::update::del_add::{DelAdd, KvReaderDelAdd};
 
 /// This is the limit where using a byteorder became less size efficient
 /// than using a direct roaring encoding, it is also the point where we are able
@@ -60,12 +61,16 @@ impl CboRoaringBitmapCodec {
     /// if the merged values length is under the threshold, values are directly
     /// serialized in the buffer else a RoaringBitmap is created from the
     /// values and is serialized in the buffer.
-    pub fn merge_into(slices: &[Cow<[u8]>], buffer: &mut Vec<u8>) -> io::Result<()> {
+    pub fn merge_into<I, A>(slices: I, buffer: &mut Vec<u8>) -> io::Result<()>
+    where
+        I: IntoIterator<Item = A>,
+        A: AsRef<[u8]>,
+    {
         let mut roaring = RoaringBitmap::new();
         let mut vec = Vec::new();
 
         for bytes in slices {
-            if bytes.len() <= THRESHOLD * size_of::<u32>() {
+            if bytes.as_ref().len() <= THRESHOLD * size_of::<u32>() {
                 let mut reader = bytes.as_ref();
                 while let Ok(integer) = reader.read_u32::<NativeEndian>() {
                     vec.push(integer);
@@ -85,7 +90,7 @@ impl CboRoaringBitmapCodec {
                 }
             } else {
                 // We can unwrap safely because the vector is sorted upper.
-                let roaring = RoaringBitmap::from_sorted_iter(vec.into_iter()).unwrap();
+                let roaring = RoaringBitmap::from_sorted_iter(vec).unwrap();
                 roaring.serialize_into(buffer)?;
             }
         } else {
@@ -95,6 +100,33 @@ impl CboRoaringBitmapCodec {
 
         Ok(())
     }
+
+    /// Merges a DelAdd delta into a CboRoaringBitmap.
+    pub fn merge_deladd_into<'a>(
+        deladd: KvReaderDelAdd<'_>,
+        previous: &[u8],
+        buffer: &'a mut Vec<u8>,
+    ) -> io::Result<Option<&'a [u8]>> {
+        // Deserialize the bitmap that is already there
+        let mut previous = Self::deserialize_from(previous)?;
+
+        // Remove integers we no more want in the previous bitmap
+        if let Some(value) = deladd.get(DelAdd::Deletion) {
+            previous -= Self::deserialize_from(value)?;
+        }
+
+        // Insert the new integers we want in the previous bitmap
+        if let Some(value) = deladd.get(DelAdd::Addition) {
+            previous |= Self::deserialize_from(value)?;
+        }
+
+        if previous.is_empty() {
+            return Ok(None);
+        }
+
+        Self::serialize_into(&previous, buffer);
+        Ok(Some(&buffer[..]))
+    }
 }
 
 impl heed::BytesDecode<'_> for CboRoaringBitmapCodec {

milli/src/search/facet/facet_sort_ascending.rs

@@ -13,7 +13,7 @@ use crate::heed_codec::ByteSliceRefCodec;
 /// The documents returned by the iterator are grouped by the facet values that
 /// determined their rank. For example, given the documents:
 ///
-/// ```ignore
+/// ```text
 /// 0: { "colour": ["blue", "green"] }
 /// 1: { "colour": ["blue", "red"] }
 /// 2: { "colour": ["orange", "red"] }
@@ -22,7 +22,7 @@ use crate::heed_codec::ByteSliceRefCodec;
 /// ```
 /// Then calling the function on the candidates `[0, 2, 3, 4]` will return an iterator
 /// over the following elements:
-/// ```ignore
+/// ```text
 /// [0, 4]  // corresponds to all the documents within the candidates that have the facet value "blue"
 /// [3]     // same for "green"
 /// [2]     // same for "orange"

milli/src/search/facet/filter.rs

@@ -223,12 +223,9 @@ impl<'a> Filter<'a> {
 impl<'a> Filter<'a> {
     pub fn evaluate(&self, rtxn: &heed::RoTxn, index: &Index) -> Result<RoaringBitmap> {
         // to avoid doing this for each recursive call we're going to do it ONCE ahead of time
-        let soft_deleted_documents = index.soft_deleted_documents_ids(rtxn)?;
         let filterable_fields = index.filterable_fields(rtxn)?;
 
-        // and finally we delete all the soft_deleted_documents, again, only once at the very end
         self.inner_evaluate(rtxn, index, &filterable_fields)
-            .map(|result| result - soft_deleted_documents)
     }
 
     fn evaluate_operator(

milli/src/search/new/db_cache.rs

@@ -12,7 +12,7 @@ use super::Word;
 use crate::heed_codec::{BytesDecodeOwned, StrBEU16Codec};
 use crate::update::{merge_cbo_roaring_bitmaps, MergeFn};
 use crate::{
-    CboRoaringBitmapCodec, CboRoaringBitmapLenCodec, Result, RoaringBitmapCodec, SearchContext,
+    CboRoaringBitmapCodec, CboRoaringBitmapLenCodec, Result, SearchContext, U8StrStrCodec,
 };
 
 /// A cache storing pointers to values in the LMDB databases.
@@ -25,7 +25,7 @@ pub struct DatabaseCache<'ctx> {
     pub word_pair_proximity_docids:
         FxHashMap<(u8, Interned<String>, Interned<String>), Option<Cow<'ctx, [u8]>>>,
     pub word_prefix_pair_proximity_docids:
-        FxHashMap<(u8, Interned<String>, Interned<String>), Option<Cow<'ctx, [u8]>>>,
+        FxHashMap<(u8, Interned<String>, Interned<String>), Option<RoaringBitmap>>,
     pub prefix_word_pair_proximity_docids:
         FxHashMap<(u8, Interned<String>, Interned<String>), Option<Cow<'ctx, [u8]>>>,
     pub word_docids: FxHashMap<Interned<String>, Option<Cow<'ctx, [u8]>>>,
@@ -168,7 +168,7 @@ impl<'ctx> SearchContext<'ctx> {
                     merge_cbo_roaring_bitmaps,
                 )
             }
-            None => DatabaseCache::get_value::<_, _, RoaringBitmapCodec>(
+            None => DatabaseCache::get_value::<_, _, CboRoaringBitmapCodec>(
                 self.txn,
                 word,
                 self.word_interner.get(word).as_str(),
@@ -182,7 +182,7 @@ impl<'ctx> SearchContext<'ctx> {
         &mut self,
         word: Interned<String>,
     ) -> Result<Option<RoaringBitmap>> {
-        DatabaseCache::get_value::<_, _, RoaringBitmapCodec>(
+        DatabaseCache::get_value::<_, _, CboRoaringBitmapCodec>(
             self.txn,
             word,
             self.word_interner.get(word).as_str(),
@@ -230,7 +230,7 @@ impl<'ctx> SearchContext<'ctx> {
                     merge_cbo_roaring_bitmaps,
                 )
             }
-            None => DatabaseCache::get_value::<_, _, RoaringBitmapCodec>(
+            None => DatabaseCache::get_value::<_, _, CboRoaringBitmapCodec>(
                 self.txn,
                 prefix,
                 self.word_interner.get(prefix).as_str(),
@@ -244,7 +244,7 @@ impl<'ctx> SearchContext<'ctx> {
         &mut self,
         prefix: Interned<String>,
     ) -> Result<Option<RoaringBitmap>> {
-        DatabaseCache::get_value::<_, _, RoaringBitmapCodec>(
+        DatabaseCache::get_value::<_, _, CboRoaringBitmapCodec>(
             self.txn,
             prefix,
             self.word_interner.get(prefix).as_str(),
@@ -297,35 +297,47 @@ impl<'ctx> SearchContext<'ctx> {
         prefix2: Interned<String>,
         proximity: u8,
     ) -> Result<Option<RoaringBitmap>> {
-        DatabaseCache::get_value::<_, _, CboRoaringBitmapCodec>(
+        let docids = match self
-            self.txn,
+            .db_cache
-            (proximity, word1, prefix2),
+            .word_prefix_pair_proximity_docids
-            &(
+            .entry((proximity, word1, prefix2))
-                proximity,
+        {
-                self.word_interner.get(word1).as_str(),
+            Entry::Occupied(docids) => docids.get().clone(),
-                self.word_interner.get(prefix2).as_str(),
+            Entry::Vacant(entry) => {
-            ),
+                // compute docids using prefix iter and store the result in the cache.
-            &mut self.db_cache.word_prefix_pair_proximity_docids,
+                let key = U8StrStrCodec::bytes_encode(&(
-            self.index.word_prefix_pair_proximity_docids.remap_data_type::<ByteSlice>(),
+                    proximity,
-        )
+                    self.word_interner.get(word1).as_str(),
+                    self.word_interner.get(prefix2).as_str(),
+                ))
+                .unwrap()
+                .into_owned();
+                let mut prefix_docids = RoaringBitmap::new();
+                let remap_key_type = self
+                    .index
+                    .word_pair_proximity_docids
+                    .remap_key_type::<ByteSlice>()
+                    .prefix_iter(self.txn, &key)?;
+                for result in remap_key_type {
+                    let (_, docids) = result?;
+
+                    prefix_docids |= docids;
+                }
+                entry.insert(Some(prefix_docids.clone()));
+                Some(prefix_docids)
+            }
+        };
+        Ok(docids)
     }
+
     pub fn get_db_prefix_word_pair_proximity_docids(
         &mut self,
         left_prefix: Interned<String>,
         right: Interned<String>,
         proximity: u8,
     ) -> Result<Option<RoaringBitmap>> {
-        DatabaseCache::get_value::<_, _, CboRoaringBitmapCodec>(
+        // only accept exact matches on reverted positions
-            self.txn,
+        self.get_db_word_pair_proximity_docids(left_prefix, right, proximity)
-            (proximity, left_prefix, right),
-            &(
-                proximity,
-                self.word_interner.get(left_prefix).as_str(),
-                self.word_interner.get(right).as_str(),
-            ),
-            &mut self.db_cache.prefix_word_pair_proximity_docids,
-            self.index.prefix_word_pair_proximity_docids.remap_data_type::<ByteSlice>(),
-        )
     }
 
     pub fn get_db_word_fid_docids(

milli/src/search/new/tests/proximity.rs

@@ -371,7 +371,7 @@ fn test_proximity_prefix_db() {
     s.scoring_strategy(crate::score_details::ScoringStrategy::Detailed);
     s.query("best s");
     let SearchResult { documents_ids, document_scores, .. } = s.execute().unwrap();
-    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[10, 13, 9, 12, 6, 7, 8, 11, 15]");
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[10, 9, 6, 7, 8, 11, 12, 13, 15]");
     insta::assert_snapshot!(format!("{document_scores:#?}"));
     let texts = collect_field_values(&index, &txn, "text", &documents_ids);
 
@@ -379,13 +379,13 @@ fn test_proximity_prefix_db() {
     insta::assert_debug_snapshot!(texts, @r###"
     [
         "\"this is the best summer meal\"",
-        "\"summer best\"",
         "\"this is the best meal of summer\"",
-        "\"summer x best\"",
         "\"this is the best meal I have ever had in such a beautiful summer day\"",
         "\"this is the best cooked meal of the summer\"",
         "\"this is the best meal of the summer\"",
         "\"summer x y best\"",
+        "\"summer x best\"",
+        "\"summer best\"",
         "\"this is the best meal I have ever had in such a beautiful winter day\"",
     ]
     "###);
@@ -423,17 +423,17 @@ fn test_proximity_prefix_db() {
     s.scoring_strategy(crate::score_details::ScoringStrategy::Detailed);
     s.query("best win");
     let SearchResult { documents_ids, document_scores, .. } = s.execute().unwrap();
-    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[15, 16, 17, 18, 19, 20, 21, 22]");
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[19, 18, 15, 16, 17, 20, 21, 22]");
     insta::assert_snapshot!(format!("{document_scores:#?}"));
     let texts = collect_field_values(&index, &txn, "text", &documents_ids);
 
     insta::assert_debug_snapshot!(texts, @r###"
     [
+        "\"this is the best winter meal\"",
+        "\"this is the best meal of winter\"",
         "\"this is the best meal I have ever had in such a beautiful winter day\"",
         "\"this is the best cooked meal of the winter\"",
         "\"this is the best meal of the winter\"",
-        "\"this is the best meal of winter\"",
-        "\"this is the best winter meal\"",
         "\"winter x y best\"",
         "\"winter x best\"",
         "\"winter best\"",
@@ -471,20 +471,20 @@ fn test_proximity_prefix_db() {
     s.scoring_strategy(crate::score_details::ScoringStrategy::Detailed);
     s.query("best wi");
     let SearchResult { documents_ids, document_scores, .. } = s.execute().unwrap();
-    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[19, 22, 18, 21, 15, 16, 17, 20]");
+    insta::assert_snapshot!(format!("{documents_ids:?}"), @"[19, 18, 15, 16, 17, 20, 21, 22]");
     insta::assert_snapshot!(format!("{document_scores:#?}"));
     let texts = collect_field_values(&index, &txn, "text", &documents_ids);
 
     insta::assert_debug_snapshot!(texts, @r###"
     [
         "\"this is the best winter meal\"",
-        "\"winter best\"",
         "\"this is the best meal of winter\"",
-        "\"winter x best\"",
         "\"this is the best meal I have ever had in such a beautiful winter day\"",
         "\"this is the best cooked meal of the winter\"",
         "\"this is the best meal of the winter\"",
         "\"winter x y best\"",
+        "\"winter x best\"",
+        "\"winter best\"",
     ]
     "###);
 }

milli/src/search/new/tests/snapshots/milli__search__new__tests__proximity__proximity_prefix_db-14.snap

@@ -11,14 +11,6 @@ expression: "format!(\"{document_scores:#?}\")"
             },
         ),
     ],
-    [
-        Proximity(
-            Rank {
-                rank: 3,
-                max_rank: 4,
-            },
-        ),
-    ],
     [
         Proximity(
             Rank {
@@ -30,7 +22,15 @@ expression: "format!(\"{document_scores:#?}\")"
     [
         Proximity(
             Rank {
-                rank: 2,
+                rank: 1,
+                max_rank: 4,
+            },
+        ),
+    ],
+    [
+        Proximity(
+            Rank {
+                rank: 1,
                 max_rank: 4,
             },
         ),

milli/src/search/new/tests/snapshots/milli__search__new__tests__proximity__proximity_prefix_db-2.snap

@@ -11,14 +11,6 @@ expression: "format!(\"{document_scores:#?}\")"
             },
         ),
     ],
-    [
-        Proximity(
-            Rank {
-                rank: 3,
-                max_rank: 4,
-            },
-        ),
-    ],
     [
         Proximity(
             Rank {
@@ -30,7 +22,15 @@ expression: "format!(\"{document_scores:#?}\")"
     [
         Proximity(
             Rank {
-                rank: 2,
+                rank: 1,
+                max_rank: 4,
+            },
+        ),
+    ],
+    [
+        Proximity(
+            Rank {
+                rank: 1,
                 max_rank: 4,
             },
         ),

milli/src/search/new/tests/snapshots/milli__search__new__tests__proximity__proximity_prefix_db-8.snap

@@ -6,7 +6,7 @@ expression: "format!(\"{document_scores:#?}\")"
     [
         Proximity(
             Rank {
-                rank: 1,
+                rank: 4,
                 max_rank: 4,
             },
         ),
@@ -14,7 +14,7 @@ expression: "format!(\"{document_scores:#?}\")"
     [
         Proximity(
             Rank {
-                rank: 1,
+                rank: 2,
                 max_rank: 4,
             },
         ),

milli/src/search/new/tests/sort.rs

@@ -13,6 +13,7 @@ This module tests the `sort` ranking rule:
 
 use big_s::S;
 use maplit::hashset;
+use meili_snap::insta;
 
 use crate::index::tests::TempIndex;
 use crate::search::new::tests::collect_field_values;

milli/src/snapshot_tests.rs

@@ -4,9 +4,8 @@ use std::path::Path;
 
 use roaring::RoaringBitmap;
 
-use crate::facet::FacetType;
 use crate::heed_codec::facet::{FacetGroupKey, FacetGroupValue};
-use crate::{make_db_snap_from_iter, obkv_to_json, ExternalDocumentsIds, Index};
+use crate::{make_db_snap_from_iter, obkv_to_json, Index};
 
 #[track_caller]
 pub fn default_db_snapshot_settings_for_test(name: Option<&str>) -> (insta::Settings, String) {
@@ -98,7 +97,6 @@ Create a snapshot test of the given database.
     - `facet_id_string_docids`
     - `documents_ids`
     - `stop_words`
-    - `soft_deleted_documents_ids`
     - `field_distribution`
     - `fields_ids_map`
     - `geo_faceted_documents_ids`
@@ -221,22 +219,6 @@ pub fn snap_word_pair_proximity_docids(index: &Index) -> String {
         &format!("{proximity:<2} {word1:<16} {word2:<16} {}", display_bitmap(&b))
     })
 }
-pub fn snap_word_prefix_pair_proximity_docids(index: &Index) -> String {
-    make_db_snap_from_iter!(index, word_prefix_pair_proximity_docids, |(
-        (proximity, word1, prefix),
-        b,
-    )| {
-        &format!("{proximity:<2} {word1:<16} {prefix:<4} {}", display_bitmap(&b))
-    })
-}
-pub fn snap_prefix_word_pair_proximity_docids(index: &Index) -> String {
-    make_db_snap_from_iter!(index, prefix_word_pair_proximity_docids, |(
-        (proximity, prefix, word2),
-        b,
-    )| {
-        &format!("{proximity:<2} {prefix:<4} {word2:<16} {}", display_bitmap(&b))
-    })
-}
 pub fn snap_word_position_docids(index: &Index) -> String {
     make_db_snap_from_iter!(index, word_position_docids, |((word, position), b)| {
         &format!("{word:<16} {position:<6} {}", display_bitmap(&b))
@@ -308,12 +290,6 @@ pub fn snap_stop_words(index: &Index) -> String {
     let snap = format!("{stop_words:?}");
     snap
 }
-pub fn snap_soft_deleted_documents_ids(index: &Index) -> String {
-    let rtxn = index.read_txn().unwrap();
-    let soft_deleted_documents_ids = index.soft_deleted_documents_ids(&rtxn).unwrap();
-
-    display_bitmap(&soft_deleted_documents_ids)
-}
 pub fn snap_field_distributions(index: &Index) -> String {
     let rtxn = index.read_txn().unwrap();
     let mut snap = String::new();
@@ -340,50 +316,21 @@ pub fn snap_geo_faceted_documents_ids(index: &Index) -> String {
 }
 pub fn snap_external_documents_ids(index: &Index) -> String {
     let rtxn = index.read_txn().unwrap();
-    let ExternalDocumentsIds { soft, hard, .. } = index.external_documents_ids(&rtxn).unwrap();
+    let external_ids = index.external_documents_ids().to_hash_map(&rtxn).unwrap();
+    // ensure fixed order (not guaranteed by hashmap)
+    let mut external_ids: Vec<(String, u32)> = external_ids.into_iter().collect();
+    external_ids.sort_by(|(l, _), (r, _)| l.cmp(r));
 
     let mut snap = String::new();
 
-    writeln!(&mut snap, "soft:").unwrap();
+    writeln!(&mut snap, "docids:").unwrap();
-    let stream_soft = soft.stream();
+    for (key, id) in external_ids {
-    let soft_external_ids = stream_soft.into_str_vec().unwrap();
-    for (key, id) in soft_external_ids {
-        writeln!(&mut snap, "{key:<24} {id}").unwrap();
-    }
-    writeln!(&mut snap, "hard:").unwrap();
-    let stream_hard = hard.stream();
-    let hard_external_ids = stream_hard.into_str_vec().unwrap();
-    for (key, id) in hard_external_ids {
         writeln!(&mut snap, "{key:<24} {id}").unwrap();
     }
 
     snap
 }
-pub fn snap_number_faceted_documents_ids(index: &Index) -> String {
-    let rtxn = index.read_txn().unwrap();
-    let fields_ids_map = index.fields_ids_map(&rtxn).unwrap();
-    let mut snap = String::new();
-    for field_id in fields_ids_map.ids() {
-        let number_faceted_documents_ids =
-            index.faceted_documents_ids(&rtxn, field_id, FacetType::Number).unwrap();
-        writeln!(&mut snap, "{field_id:<3} {}", display_bitmap(&number_faceted_documents_ids))
-            .unwrap();
-    }
-    snap
-}
-pub fn snap_string_faceted_documents_ids(index: &Index) -> String {
-    let rtxn = index.read_txn().unwrap();
-    let fields_ids_map = index.fields_ids_map(&rtxn).unwrap();
 
-    let mut snap = String::new();
-    for field_id in fields_ids_map.ids() {
-        let string_faceted_documents_ids =
-            index.faceted_documents_ids(&rtxn, field_id, FacetType::String).unwrap();
-        writeln!(&mut snap, "{field_id:<3} {}", display_bitmap(&string_faceted_documents_ids))
-            .unwrap();
-    }
-    snap
-}
 pub fn snap_words_fst(index: &Index) -> String {
     let rtxn = index.read_txn().unwrap();
     let words_fst = index.words_fst(&rtxn).unwrap();
@@ -516,9 +463,6 @@ macro_rules! full_snap_of_db {
     ($index:ident, stop_words) => {{
         $crate::snapshot_tests::snap_stop_words(&$index)
     }};
-    ($index:ident, soft_deleted_documents_ids) => {{
-        $crate::snapshot_tests::snap_soft_deleted_documents_ids(&$index)
-    }};
     ($index:ident, field_distribution) => {{
         $crate::snapshot_tests::snap_field_distributions(&$index)
     }};
@@ -531,12 +475,6 @@ macro_rules! full_snap_of_db {
     ($index:ident, external_documents_ids) => {{
         $crate::snapshot_tests::snap_external_documents_ids(&$index)
     }};
-    ($index:ident, number_faceted_documents_ids) => {{
-        $crate::snapshot_tests::snap_number_faceted_documents_ids(&$index)
-    }};
-    ($index:ident, string_faceted_documents_ids) => {{
-        $crate::snapshot_tests::snap_string_faceted_documents_ids(&$index)
-    }};
     ($index:ident, words_fst) => {{
         $crate::snapshot_tests::snap_words_fst(&$index)
     }};

milli/src/update/available_documents_ids.rs

@@ -8,16 +8,11 @@ pub struct AvailableDocumentsIds {
 }
 
 impl AvailableDocumentsIds {
-    pub fn from_documents_ids(
+    pub fn from_documents_ids(docids: &RoaringBitmap) -> AvailableDocumentsIds {
-        docids: &RoaringBitmap,
+        match docids.max() {
-        soft_deleted_docids: &RoaringBitmap,
-    ) -> AvailableDocumentsIds {
-        let used_docids = docids | soft_deleted_docids;
-
-        match used_docids.max() {
             Some(last_id) => {
                 let mut available = RoaringBitmap::from_iter(0..last_id);
-                available -= used_docids;
+                available -= docids;
 
                 let iter = match last_id.checked_add(1) {
                     Some(id) => id..=u32::max_value(),
@@ -50,7 +45,7 @@ mod tests {
     #[test]
     fn empty() {
         let base = RoaringBitmap::new();
-        let left = AvailableDocumentsIds::from_documents_ids(&base, &RoaringBitmap::new());
+        let left = AvailableDocumentsIds::from_documents_ids(&base);
         let right = 0..=u32::max_value();
         left.zip(right).take(500).for_each(|(l, r)| assert_eq!(l, r));
     }
@@ -63,28 +58,8 @@ mod tests {
         base.insert(100);
         base.insert(405);
 
-        let left = AvailableDocumentsIds::from_documents_ids(&base, &RoaringBitmap::new());
+        let left = AvailableDocumentsIds::from_documents_ids(&base);
         let right = (0..=u32::max_value()).filter(|&n| n != 0 && n != 10 && n != 100 && n != 405);
         left.zip(right).take(500).for_each(|(l, r)| assert_eq!(l, r));
     }
-
-    #[test]
-    fn soft_deleted() {
-        let mut base = RoaringBitmap::new();
-        base.insert(0);
-        base.insert(10);
-        base.insert(100);
-        base.insert(405);
-
-        let mut soft_deleted = RoaringBitmap::new();
-        soft_deleted.insert(1);
-        soft_deleted.insert(11);
-        soft_deleted.insert(101);
-        soft_deleted.insert(406);
-
-        let left = AvailableDocumentsIds::from_documents_ids(&base, &soft_deleted);
-        let right =
-            (0..=u32::max_value()).filter(|&n| ![0, 1, 10, 11, 100, 101, 405, 406].contains(&n));
-        left.zip(right).take(500).for_each(|(l, r)| assert_eq!(l, r));
-    }
 }

milli/src/update/clear_documents.rs

@@ -1,8 +1,7 @@
 use roaring::RoaringBitmap;
 use time::OffsetDateTime;
 
-use crate::facet::FacetType;
+use crate::{FieldDistribution, Index, Result};
-use crate::{ExternalDocumentsIds, FieldDistribution, Index, Result};
 
 pub struct ClearDocuments<'t, 'u, 'i> {
     wtxn: &'t mut heed::RwTxn<'i, 'u>,
@@ -21,13 +20,12 @@ impl<'t, 'u, 'i> ClearDocuments<'t, 'u, 'i> {
         let Index {
             env: _env,
             main: _main,
+            external_documents_ids,
             word_docids,
             exact_word_docids,
             word_prefix_docids,
             exact_word_prefix_docids,
             word_pair_proximity_docids,
-            word_prefix_pair_proximity_docids,
-            prefix_word_pair_proximity_docids,
             word_position_docids,
             word_fid_docids,
             field_id_word_count_docids,
@@ -51,43 +49,23 @@ impl<'t, 'u, 'i> ClearDocuments<'t, 'u, 'i> {
 
         // We retrieve the number of documents ids that we are deleting.
         let number_of_documents = self.index.number_of_documents(self.wtxn)?;
-        let faceted_fields = self.index.faceted_fields_ids(self.wtxn)?;
 
         // We clean some of the main engine datastructures.
         self.index.put_words_fst(self.wtxn, &fst::Set::default())?;
         self.index.put_words_prefixes_fst(self.wtxn, &fst::Set::default())?;
-        self.index.put_external_documents_ids(self.wtxn, &ExternalDocumentsIds::default())?;
         self.index.put_documents_ids(self.wtxn, &empty_roaring)?;
-        self.index.put_soft_deleted_documents_ids(self.wtxn, &empty_roaring)?;
         self.index.put_field_distribution(self.wtxn, &FieldDistribution::default())?;
         self.index.delete_geo_rtree(self.wtxn)?;
         self.index.delete_geo_faceted_documents_ids(self.wtxn)?;
         self.index.delete_vector_hnsw(self.wtxn)?;
 
-        // We clean all the faceted documents ids.
-        for field_id in faceted_fields {
-            self.index.put_faceted_documents_ids(
-                self.wtxn,
-                field_id,
-                FacetType::Number,
-                &empty_roaring,
-            )?;
-            self.index.put_faceted_documents_ids(
-                self.wtxn,
-                field_id,
-                FacetType::String,
-                &empty_roaring,
-            )?;
-        }
-
         // Clear the other databases.
+        external_documents_ids.clear(self.wtxn)?;
         word_docids.clear(self.wtxn)?;
         exact_word_docids.clear(self.wtxn)?;
         word_prefix_docids.clear(self.wtxn)?;
         exact_word_prefix_docids.clear(self.wtxn)?;
         word_pair_proximity_docids.clear(self.wtxn)?;
-        word_prefix_pair_proximity_docids.clear(self.wtxn)?;
-        prefix_word_pair_proximity_docids.clear(self.wtxn)?;
         word_position_docids.clear(self.wtxn)?;
         word_fid_docids.clear(self.wtxn)?;
         field_id_word_count_docids.clear(self.wtxn)?;
@@ -140,7 +118,7 @@ mod tests {
 
         assert!(index.words_fst(&rtxn).unwrap().is_empty());
         assert!(index.words_prefixes_fst(&rtxn).unwrap().is_empty());
-        assert!(index.external_documents_ids(&rtxn).unwrap().is_empty());
+        assert!(index.external_documents_ids().is_empty(&rtxn).unwrap());
         assert!(index.documents_ids(&rtxn).unwrap().is_empty());
         assert!(index.field_distribution(&rtxn).unwrap().is_empty());
         assert!(index.geo_rtree(&rtxn).unwrap().is_none());
@@ -150,7 +128,6 @@ mod tests {
         assert!(index.word_prefix_docids.is_empty(&rtxn).unwrap());
         assert!(index.word_pair_proximity_docids.is_empty(&rtxn).unwrap());
         assert!(index.field_id_word_count_docids.is_empty(&rtxn).unwrap());
-        assert!(index.word_prefix_pair_proximity_docids.is_empty(&rtxn).unwrap());
         assert!(index.facet_id_f64_docids.is_empty(&rtxn).unwrap());
         assert!(index.facet_id_string_docids.is_empty(&rtxn).unwrap());
         assert!(index.field_id_docid_facet_f64s.is_empty(&rtxn).unwrap());

milli/src/update/del_add.rs

@@ -0,0 +1,125 @@
+use obkv::Key;
+
+pub type KvWriterDelAdd<W> = obkv::KvWriter<W, DelAdd>;
+pub type KvReaderDelAdd<'a> = obkv::KvReader<'a, DelAdd>;
+
+/// DelAdd defines the new value to add in the database and old value to delete from the database.
+///
+/// Its used in an OBKV to be serialized in grenad files.
+#[repr(u8)]
+#[derive(Clone, Copy, PartialOrd, PartialEq, Debug)]
+pub enum DelAdd {
+    Deletion = 0,
+    Addition = 1,
+}
+
+impl Key for DelAdd {
+    const BYTES_SIZE: usize = std::mem::size_of::<DelAdd>();
+    type BYTES = [u8; Self::BYTES_SIZE];
+
+    fn to_be_bytes(&self) -> Self::BYTES {
+        u8::to_be_bytes(*self as u8)
+    }
+
+    fn from_be_bytes(array: Self::BYTES) -> Self {
+        match u8::from_be_bytes(array) {
+            0 => Self::Deletion,
+            1 => Self::Addition,
+            otherwise => unreachable!("DelAdd has only 2 variants, unknown variant: {}", otherwise),
+        }
+    }
+}
+
+/// Creates a Kv<K, Kv<DelAdd, value>> from Kv<K, value>
+///
+/// Deletion: put all the values under DelAdd::Deletion
+/// Addition: put all the values under DelAdd::Addition,
+/// DeletionAndAddition: put all the values under DelAdd::Deletion and DelAdd::Addition,
+pub fn into_del_add_obkv<K: obkv::Key + PartialOrd>(
+    reader: obkv::KvReader<K>,
+    operation: DelAddOperation,
+    buffer: &mut Vec<u8>,
+) -> Result<(), std::io::Error> {
+    let mut writer = obkv::KvWriter::new(buffer);
+    let mut value_buffer = Vec::new();
+    for (key, value) in reader.iter() {
+        value_buffer.clear();
+        let mut value_writer = KvWriterDelAdd::new(&mut value_buffer);
+        if matches!(operation, DelAddOperation::Deletion | DelAddOperation::DeletionAndAddition) {
+            value_writer.insert(DelAdd::Deletion, value)?;
+        }
+        if matches!(operation, DelAddOperation::Addition | DelAddOperation::DeletionAndAddition) {
+            value_writer.insert(DelAdd::Addition, value)?;
+        }
+        value_writer.finish()?;
+        writer.insert(key, &value_buffer)?;
+    }
+
+    writer.finish()
+}
+
+/// Enum controlling the side of the DelAdd obkv in which the provided value will be written.
+#[derive(Debug, Clone, Copy)]
+pub enum DelAddOperation {
+    Deletion,
+    Addition,
+    DeletionAndAddition,
+}
+
+/// Creates a Kv<K, Kv<DelAdd, value>> from two Kv<K, value>
+///
+/// putting each deletion obkv's keys under an DelAdd::Deletion
+/// and putting each addition obkv's keys under an DelAdd::Addition
+pub fn del_add_from_two_obkvs<K: obkv::Key + PartialOrd + Ord>(
+    deletion: obkv::KvReader<K>,
+    addition: obkv::KvReader<K>,
+    buffer: &mut Vec<u8>,
+) -> Result<(), std::io::Error> {
+    use itertools::merge_join_by;
+    use itertools::EitherOrBoth::{Both, Left, Right};
+
+    let mut writer = obkv::KvWriter::new(buffer);
+    let mut value_buffer = Vec::new();
+
+    for eob in merge_join_by(deletion.iter(), addition.iter(), |(b, _), (u, _)| b.cmp(u)) {
+        value_buffer.clear();
+        match eob {
+            Left((k, v)) => {
+                let mut value_writer = KvWriterDelAdd::new(&mut value_buffer);
+                value_writer.insert(DelAdd::Deletion, v).unwrap();
+                writer.insert(k, value_writer.into_inner()?).unwrap();
+            }
+            Right((k, v)) => {
+                let mut value_writer = KvWriterDelAdd::new(&mut value_buffer);
+                value_writer.insert(DelAdd::Addition, v).unwrap();
+                writer.insert(k, value_writer.into_inner()?).unwrap();
+            }
+            Both((k, deletion), (_, addition)) => {
+                let mut value_writer = KvWriterDelAdd::new(&mut value_buffer);
+                value_writer.insert(DelAdd::Deletion, deletion).unwrap();
+                value_writer.insert(DelAdd::Addition, addition).unwrap();
+                writer.insert(k, value_writer.into_inner()?).unwrap();
+            }
+        }
+    }
+
+    writer.finish()
+}
+
+pub fn is_noop_del_add_obkv(del_add: KvReaderDelAdd) -> bool {
+    del_add.get(DelAdd::Deletion) == del_add.get(DelAdd::Addition)
+}
+
+/// A function that extracts and returns the Add side of a DelAdd obkv.
+/// This is useful when there are no previous value in the database and
+/// therefore we don't need to do a diff with what's already there.
+///
+/// If there is no Add side we currently write an empty buffer
+/// which is a valid CboRoaringBitmap.
+#[allow(clippy::ptr_arg)] // required to avoid signature mismatch
+pub fn deladd_serialize_add_side<'a>(
+    obkv: &'a [u8],
+    _buffer: &mut Vec<u8>,
+) -> crate::Result<&'a [u8]> {
+    Ok(KvReaderDelAdd::new(obkv).get(DelAdd::Addition).unwrap_or_default())
+}

milli/src/update/facet/bulk.rs

@@ -1,10 +1,9 @@
-use std::borrow::Cow;
 use std::fs::File;
 use std::io::BufReader;
 
 use grenad::CompressionType;
 use heed::types::ByteSlice;
-use heed::{BytesEncode, Error, RoTxn, RwTxn};
+use heed::{BytesDecode, BytesEncode, Error, RoTxn, RwTxn};
 use roaring::RoaringBitmap;
 
 use super::{FACET_GROUP_SIZE, FACET_MIN_LEVEL_SIZE};
@@ -13,17 +12,15 @@ use crate::heed_codec::facet::{
     FacetGroupKey, FacetGroupKeyCodec, FacetGroupValue, FacetGroupValueCodec,
 };
 use crate::heed_codec::ByteSliceRefCodec;
+use crate::update::del_add::{DelAdd, KvReaderDelAdd};
 use crate::update::index_documents::{create_writer, valid_lmdb_key, writer_into_reader};
-use crate::{CboRoaringBitmapCodec, FieldId, Index, Result};
+use crate::{CboRoaringBitmapCodec, CboRoaringBitmapLenCodec, FieldId, Index, Result};
 
 /// Algorithm to insert elememts into the `facet_id_(string/f64)_docids` databases
 /// by rebuilding the database "from scratch".
 ///
 /// First, the new elements are inserted into the level 0 of the database. Then, the
 /// higher levels are cleared and recomputed from the content of level 0.
-///
-/// Finally, the `faceted_documents_ids` value in the main database of `Index`
-/// is updated to contain the new set of faceted documents.
 pub struct FacetsUpdateBulk<'i> {
     index: &'i Index,
     group_size: u8,
@@ -31,7 +28,7 @@ pub struct FacetsUpdateBulk<'i> {
     facet_type: FacetType,
     field_ids: Vec<FieldId>,
     // None if level 0 does not need to be updated
-    new_data: Option<grenad::Reader<BufReader<File>>>,
+    delta_data: Option<grenad::Reader<BufReader<File>>>,
 }
 
 impl<'i> FacetsUpdateBulk<'i> {
@@ -39,7 +36,7 @@ impl<'i> FacetsUpdateBulk<'i> {
         index: &'i Index,
         field_ids: Vec<FieldId>,
         facet_type: FacetType,
-        new_data: grenad::Reader<BufReader<File>>,
+        delta_data: grenad::Reader<BufReader<File>>,
         group_size: u8,
         min_level_size: u8,
     ) -> FacetsUpdateBulk<'i> {
@@ -49,7 +46,7 @@ impl<'i> FacetsUpdateBulk<'i> {
             group_size,
             min_level_size,
             facet_type,
-            new_data: Some(new_data),
+            delta_data: Some(delta_data),
         }
     }
 
@@ -64,13 +61,13 @@ impl<'i> FacetsUpdateBulk<'i> {
             group_size: FACET_GROUP_SIZE,
             min_level_size: FACET_MIN_LEVEL_SIZE,
             facet_type,
-            new_data: None,
+            delta_data: None,
         }
     }
 
     #[logging_timer::time("FacetsUpdateBulk::{}")]
     pub fn execute(self, wtxn: &mut heed::RwTxn) -> Result<()> {
-        let Self { index, field_ids, group_size, min_level_size, facet_type, new_data } = self;
+        let Self { index, field_ids, group_size, min_level_size, facet_type, delta_data } = self;
 
         let db = match facet_type {
             FacetType::String => index
@@ -81,12 +78,9 @@ impl<'i> FacetsUpdateBulk<'i> {
             }
         };
 
-        let inner = FacetsUpdateBulkInner { db, new_data, group_size, min_level_size };
+        let inner = FacetsUpdateBulkInner { db, delta_data, group_size, min_level_size };
 
-        inner.update(wtxn, &field_ids, |wtxn, field_id, all_docids| {
+        inner.update(wtxn, &field_ids)?;
-            index.put_faceted_documents_ids(wtxn, field_id, facet_type, &all_docids)?;
-            Ok(())
-        })?;
 
         Ok(())
     }
@@ -95,26 +89,19 @@ impl<'i> FacetsUpdateBulk<'i> {
 /// Implementation of `FacetsUpdateBulk` that is independent of milli's `Index` type
 pub(crate) struct FacetsUpdateBulkInner<R: std::io::Read + std::io::Seek> {
     pub db: heed::Database<FacetGroupKeyCodec<ByteSliceRefCodec>, FacetGroupValueCodec>,
-    pub new_data: Option<grenad::Reader<R>>,
+    pub delta_data: Option<grenad::Reader<R>>,
     pub group_size: u8,
     pub min_level_size: u8,
 }
 impl<R: std::io::Read + std::io::Seek> FacetsUpdateBulkInner<R> {
-    pub fn update(
+    pub fn update(mut self, wtxn: &mut RwTxn, field_ids: &[u16]) -> Result<()> {
-        mut self,
-        wtxn: &mut RwTxn,
-        field_ids: &[u16],
-        mut handle_all_docids: impl FnMut(&mut RwTxn, FieldId, RoaringBitmap) -> Result<()>,
-    ) -> Result<()> {
         self.update_level0(wtxn)?;
         for &field_id in field_ids.iter() {
             self.clear_levels(wtxn, field_id)?;
         }
 
         for &field_id in field_ids.iter() {
-            let (level_readers, all_docids) = self.compute_levels_for_field_id(field_id, wtxn)?;
+            let level_readers = self.compute_levels_for_field_id(field_id, wtxn)?;
-
-            handle_all_docids(wtxn, field_id, all_docids)?;
 
             for level_reader in level_readers {
                 let mut cursor = level_reader.into_cursor()?;
@@ -133,19 +120,27 @@ impl<R: std::io::Read + std::io::Seek> FacetsUpdateBulkInner<R> {
         self.db.delete_range(wtxn, &range).map(drop)?;
         Ok(())
     }
+
     fn update_level0(&mut self, wtxn: &mut RwTxn) -> Result<()> {
-        let new_data = match self.new_data.take() {
+        let delta_data = match self.delta_data.take() {
             Some(x) => x,
             None => return Ok(()),
         };
         if self.db.is_empty(wtxn)? {
             let mut buffer = Vec::new();
             let mut database = self.db.iter_mut(wtxn)?.remap_types::<ByteSlice, ByteSlice>();
-            let mut cursor = new_data.into_cursor()?;
+            let mut cursor = delta_data.into_cursor()?;
             while let Some((key, value)) = cursor.move_on_next()? {
                 if !valid_lmdb_key(key) {
                     continue;
                 }
+                let value = KvReaderDelAdd::new(value);
+
+                // DB is empty, it is safe to ignore Del operations
+                let Some(value) = value.get(DelAdd::Addition) else {
+                    continue;
+                };
+
                 buffer.clear();
                 // the group size for level 0
                 buffer.push(1);
@@ -157,11 +152,14 @@ impl<R: std::io::Read + std::io::Seek> FacetsUpdateBulkInner<R> {
             let mut buffer = Vec::new();
             let database = self.db.remap_types::<ByteSlice, ByteSlice>();
 
-            let mut cursor = new_data.into_cursor()?;
+            let mut cursor = delta_data.into_cursor()?;
             while let Some((key, value)) = cursor.move_on_next()? {
                 if !valid_lmdb_key(key) {
                     continue;
                 }
+
+                let value = KvReaderDelAdd::new(value);
+
                 // the value is a CboRoaringBitmap, but I still need to prepend the
                 // group size for level 0 (= 1) to it
                 buffer.clear();
@@ -169,17 +167,27 @@ impl<R: std::io::Read + std::io::Seek> FacetsUpdateBulkInner<R> {
                 // then we extend the buffer with the docids bitmap
                 match database.get(wtxn, key)? {
                     Some(prev_value) => {
+                        // prev_value is the group size for level 0, followed by the previous bitmap.
                         let old_bitmap = &prev_value[1..];
-                        CboRoaringBitmapCodec::merge_into(
+                        CboRoaringBitmapCodec::merge_deladd_into(value, old_bitmap, &mut buffer)?;
-                            &[Cow::Borrowed(value), Cow::Borrowed(old_bitmap)],
-                            &mut buffer,
-                        )?;
                     }
                     None => {
+                        // it is safe to ignore the del in that case.
+                        let Some(value) = value.get(DelAdd::Addition) else {
+                            // won't put the key in DB as the value would be empty
+                            continue;
+                        };
+
                         buffer.extend_from_slice(value);
                     }
                 };
-                database.put(wtxn, key, &buffer)?;
+                let new_bitmap = &buffer[1..];
+                // if the new bitmap is empty, let's remove it
+                if CboRoaringBitmapLenCodec::bytes_decode(new_bitmap).unwrap_or_default() == 0 {
+                    database.delete(wtxn, key)?;
+                } else {
+                    database.put(wtxn, key, &buffer)?;
+                }
             }
         }
         Ok(())
@@ -188,16 +196,10 @@ impl<R: std::io::Read + std::io::Seek> FacetsUpdateBulkInner<R> {
         &self,
         field_id: FieldId,
         txn: &RoTxn,
-    ) -> Result<(Vec<grenad::Reader<BufReader<File>>>, RoaringBitmap)> {
+    ) -> Result<Vec<grenad::Reader<BufReader<File>>>> {
-        let mut all_docids = RoaringBitmap::new();
+        let subwriters = self.compute_higher_levels(txn, field_id, 32, &mut |_, _| Ok(()))?;
-        let subwriters = self.compute_higher_levels(txn, field_id, 32, &mut |bitmaps, _| {
-            for bitmap in bitmaps {
-                all_docids |= bitmap;
-            }
-            Ok(())
-        })?;
 
-        Ok((subwriters, all_docids))
+        Ok(subwriters)
     }
     #[allow(clippy::type_complexity)]
     fn read_level_0<'t>(
@@ -491,7 +493,6 @@ mod tests {
         index.add_documents(documents).unwrap();
 
         db_snap!(index, facet_id_f64_docids, "initial", @"c34f499261f3510d862fa0283bbe843a");
-        db_snap!(index, number_faceted_documents_ids, "initial", @"01594fecbb316798ce3651d6730a4521");
     }
 
     #[test]

milli/src/update/facet/delete.rs

@@ -1,360 +0,0 @@
-use std::collections::{HashMap, HashSet};
-
-use heed::RwTxn;
-use log::debug;
-use roaring::RoaringBitmap;
-use time::OffsetDateTime;
-
-use super::{FACET_GROUP_SIZE, FACET_MAX_GROUP_SIZE, FACET_MIN_LEVEL_SIZE};
-use crate::facet::FacetType;
-use crate::heed_codec::facet::{FacetGroupKey, FacetGroupKeyCodec, FacetGroupValueCodec};
-use crate::heed_codec::ByteSliceRefCodec;
-use crate::update::{FacetsUpdateBulk, FacetsUpdateIncrementalInner};
-use crate::{FieldId, Index, Result};
-
-/// A builder used to remove elements from the `facet_id_string_docids` or `facet_id_f64_docids` databases.
-///
-/// Depending on the number of removed elements and the existing size of the database, we use either
-/// a bulk delete method or an incremental delete method.
-pub struct FacetsDelete<'i, 'b> {
-    index: &'i Index,
-    database: heed::Database<FacetGroupKeyCodec<ByteSliceRefCodec>, FacetGroupValueCodec>,
-    facet_type: FacetType,
-    affected_facet_values: HashMap<FieldId, HashSet<Vec<u8>>>,
-    docids_to_delete: &'b RoaringBitmap,
-    group_size: u8,
-    max_group_size: u8,
-    min_level_size: u8,
-}
-impl<'i, 'b> FacetsDelete<'i, 'b> {
-    pub fn new(
-        index: &'i Index,
-        facet_type: FacetType,
-        affected_facet_values: HashMap<FieldId, HashSet<Vec<u8>>>,
-        docids_to_delete: &'b RoaringBitmap,
-    ) -> Self {
-        let database = match facet_type {
-            FacetType::String => index
-                .facet_id_string_docids
-                .remap_key_type::<FacetGroupKeyCodec<ByteSliceRefCodec>>(),
-            FacetType::Number => {
-                index.facet_id_f64_docids.remap_key_type::<FacetGroupKeyCodec<ByteSliceRefCodec>>()
-            }
-        };
-        Self {
-            index,
-            database,
-            facet_type,
-            affected_facet_values,
-            docids_to_delete,
-            group_size: FACET_GROUP_SIZE,
-            max_group_size: FACET_MAX_GROUP_SIZE,
-            min_level_size: FACET_MIN_LEVEL_SIZE,
-        }
-    }
-
-    pub fn execute(self, wtxn: &mut RwTxn) -> Result<()> {
-        debug!("Computing and writing the facet values levels docids into LMDB on disk...");
-        self.index.set_updated_at(wtxn, &OffsetDateTime::now_utc())?;
-
-        for (field_id, affected_facet_values) in self.affected_facet_values {
-            // This is an incorrect condition, since we assume that the length of the database is equal
-            // to the number of facet values for the given field_id. It means that in some cases, we might
-            // wrongly choose the incremental indexer over the bulk indexer. But the only case where that could
-            // really be a performance problem is when we fully delete a large ratio of all facet values for
-            // each field id. This would almost never happen. Still, to be overly cautious, I have added a
-            // 2x penalty to the incremental indexer. That is, instead of assuming a 70x worst-case performance
-            // penalty to the incremental indexer, we assume a 150x worst-case performance penalty instead.
-            if affected_facet_values.len() >= (self.database.len(wtxn)? / 150) {
-                // Bulk delete
-                let mut modified = false;
-
-                for facet_value in affected_facet_values {
-                    let key =
-                        FacetGroupKey { field_id, level: 0, left_bound: facet_value.as_slice() };
-                    let mut old = self.database.get(wtxn, &key)?.unwrap();
-                    let previous_len = old.bitmap.len();
-                    old.bitmap -= self.docids_to_delete;
-                    if old.bitmap.is_empty() {
-                        modified = true;
-                        self.database.delete(wtxn, &key)?;
-                    } else if old.bitmap.len() != previous_len {
-                        modified = true;
-                        self.database.put(wtxn, &key, &old)?;
-                    }
-                }
-                if modified {
-                    let builder = FacetsUpdateBulk::new_not_updating_level_0(
-                        self.index,
-                        vec![field_id],
-                        self.facet_type,
-                    );
-                    builder.execute(wtxn)?;
-                }
-            } else {
-                // Incremental
-                let inc = FacetsUpdateIncrementalInner {
-                    db: self.database,
-                    group_size: self.group_size,
-                    min_level_size: self.min_level_size,
-                    max_group_size: self.max_group_size,
-                };
-                for facet_value in affected_facet_values {
-                    inc.delete(wtxn, field_id, facet_value.as_slice(), self.docids_to_delete)?;
-                }
-            }
-        }
-        Ok(())
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use std::iter::FromIterator;
-
-    use big_s::S;
-    use maplit::hashset;
-    use rand::seq::SliceRandom;
-    use rand::SeedableRng;
-    use roaring::RoaringBitmap;
-
-    use crate::db_snap;
-    use crate::documents::documents_batch_reader_from_objects;
-    use crate::index::tests::TempIndex;
-    use crate::update::facet::test_helpers::ordered_string;
-    use crate::update::{DeleteDocuments, DeletionStrategy};
-
-    #[test]
-    fn delete_mixed_incremental_and_bulk() {
-        // The point of this test is to create an index populated with documents
-        // containing different filterable attributes. Then, we delete a bunch of documents
-        // such that a mix of the incremental and bulk indexer is used (depending on the field id)
-        let index = TempIndex::new_with_map_size(4096 * 1000 * 100);
-
-        index
-            .update_settings(|settings| {
-                settings.set_filterable_fields(
-                    hashset! { S("id"), S("label"), S("timestamp"), S("colour") },
-                );
-            })
-            .unwrap();
-
-        let mut documents = vec![];
-        for i in 0..1000 {
-            documents.push(
-                serde_json::json! {
-                    {
-                        "id": i,
-                        "label": i / 10,
-                        "colour": i / 100,
-                        "timestamp": i / 2,
-                    }
-                }
-                .as_object()
-                .unwrap()
-                .clone(),
-            );
-        }
-
-        let documents = documents_batch_reader_from_objects(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, facet_id_f64_docids, 1, @"550cd138d6fe31ccdd42cd5392fbd576");
-        db_snap!(index, number_faceted_documents_ids, 1, @"9a0ea88e7c9dcf6dc0ef0b601736ffcf");
-
-        let mut wtxn = index.env.write_txn().unwrap();
-
-        let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-        builder.strategy(DeletionStrategy::AlwaysHard);
-        builder.delete_documents(&RoaringBitmap::from_iter(0..100));
-        // by deleting the first 100 documents, we expect that:
-        // - the "id" part of the DB will be updated in bulk, since #affected_facet_value = 100 which is > database_len / 150 (= 13)
-        // - the "label" part will be updated incrementally, since #affected_facet_value = 10 which is < 13
-        // - the "colour" part will also be updated incrementally, since #affected_values = 1 which is < 13
-        // - the "timestamp" part will be updated in bulk, since #affected_values = 50 which is > 13
-        // This has to be verified manually by inserting breakpoint/adding print statements to the code when running the test
-        builder.execute().unwrap();
-        wtxn.commit().unwrap();
-
-        db_snap!(index, soft_deleted_documents_ids, @"[]");
-        db_snap!(index, facet_id_f64_docids, 2, @"d4d5f14e7f1e1f09b86821a0b6defcc6");
-        db_snap!(index, number_faceted_documents_ids, 2, @"3570e0ac0fdb21be9ebe433f59264b56");
-    }
-
-    // Same test as above but working with string values for the facets
-    #[test]
-    fn delete_mixed_incremental_and_bulk_string() {
-        // The point of this test is to create an index populated with documents
-        // containing different filterable attributes. Then, we delete a bunch of documents
-        // such that a mix of the incremental and bulk indexer is used (depending on the field id)
-        let index = TempIndex::new_with_map_size(4096 * 1000 * 100);
-
-        index
-            .update_settings(|settings| {
-                settings.set_filterable_fields(
-                    hashset! { S("id"), S("label"), S("timestamp"), S("colour") },
-                );
-            })
-            .unwrap();
-
-        let mut documents = vec![];
-        for i in 0..1000 {
-            documents.push(
-                serde_json::json! {
-                    {
-                        "id": i,
-                        "label": ordered_string(i / 10),
-                        "colour": ordered_string(i / 100),
-                        "timestamp": ordered_string(i / 2),
-                    }
-                }
-                .as_object()
-                .unwrap()
-                .clone(),
-            );
-        }
-
-        let documents = documents_batch_reader_from_objects(documents);
-        index.add_documents(documents).unwrap();
-
-        // Note that empty strings are not stored in the facet db due to commit 4860fd452965 (comment written on 29 Nov 2022)
-        db_snap!(index, facet_id_string_docids, 1, @"5fd1bd0724c65a6dc1aafb6db93c7503");
-        db_snap!(index, string_faceted_documents_ids, 1, @"54bc15494fa81d93339f43c08fd9d8f5");
-
-        let mut wtxn = index.env.write_txn().unwrap();
-
-        let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-        builder.strategy(DeletionStrategy::AlwaysHard);
-        builder.delete_documents(&RoaringBitmap::from_iter(0..100));
-        // by deleting the first 100 documents, we expect that:
-        // - the "id" part of the DB will be updated in bulk, since #affected_facet_value = 100 which is > database_len / 150 (= 13)
-        // - the "label" part will be updated incrementally, since #affected_facet_value = 10 which is < 13
-        // - the "colour" part will also be updated incrementally, since #affected_values = 1 which is < 13
-        // - the "timestamp" part will be updated in bulk, since #affected_values = 50 which is > 13
-        // This has to be verified manually by inserting breakpoint/adding print statements to the code when running the test
-        builder.execute().unwrap();
-        wtxn.commit().unwrap();
-
-        db_snap!(index, soft_deleted_documents_ids, @"[]");
-        db_snap!(index, facet_id_string_docids, 2, @"7f9c00b29e04d58c1821202a5dda0ebc");
-        db_snap!(index, string_faceted_documents_ids, 2, @"504152afa5c94fd4e515dcdfa4c7161f");
-    }
-
-    #[test]
-    fn delete_almost_all_incrementally_string() {
-        let index = TempIndex::new_with_map_size(4096 * 1000 * 100);
-
-        index
-            .update_settings(|settings| {
-                settings.set_filterable_fields(
-                    hashset! { S("id"), S("label"), S("timestamp"), S("colour") },
-                );
-            })
-            .unwrap();
-
-        let mut documents = vec![];
-        for i in 0..1000 {
-            documents.push(
-                serde_json::json! {
-                    {
-                        "id": i,
-                        "label": ordered_string(i / 10),
-                        "colour": ordered_string(i / 100),
-                        "timestamp": ordered_string(i / 2),
-                    }
-                }
-                .as_object()
-                .unwrap()
-                .clone(),
-            );
-        }
-
-        let documents = documents_batch_reader_from_objects(documents);
-        index.add_documents(documents).unwrap();
-
-        // Note that empty strings are not stored in the facet db due to commit 4860fd452965 (comment written on 29 Nov 2022)
-        db_snap!(index, facet_id_string_docids, 1, @"5fd1bd0724c65a6dc1aafb6db93c7503");
-        db_snap!(index, string_faceted_documents_ids, 1, @"54bc15494fa81d93339f43c08fd9d8f5");
-
-        let mut rng = rand::rngs::SmallRng::from_seed([0; 32]);
-
-        let mut docids_to_delete = (0..1000).collect::<Vec<_>>();
-        docids_to_delete.shuffle(&mut rng);
-        for docid in docids_to_delete.into_iter().take(990) {
-            let mut wtxn = index.env.write_txn().unwrap();
-            let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-            builder.strategy(DeletionStrategy::AlwaysHard);
-            builder.delete_documents(&RoaringBitmap::from_iter([docid]));
-            builder.execute().unwrap();
-            wtxn.commit().unwrap();
-        }
-
-        db_snap!(index, soft_deleted_documents_ids, @"[]");
-        db_snap!(index, facet_id_string_docids, 2, @"ece56086e76d50e661fb2b58475b9f7d");
-        db_snap!(index, string_faceted_documents_ids, 2, @r###"
-        0   []
-        1   [11, 20, 73, 292, 324, 358, 381, 493, 839, 852, ]
-        2   [292, 324, 358, 381, 493, 839, 852, ]
-        3   [11, 20, 73, 292, 324, 358, 381, 493, 839, 852, ]
-        "###);
-    }
-}
-
-#[allow(unused)]
-#[cfg(test)]
-mod comparison_bench {
-    use std::iter::once;
-
-    use rand::Rng;
-    use roaring::RoaringBitmap;
-
-    use crate::heed_codec::facet::OrderedF64Codec;
-    use crate::update::facet::test_helpers::FacetIndex;
-
-    // This is a simple test to get an intuition on the relative speed
-    // of the incremental vs. bulk indexer.
-    //
-    // The benchmark shows the worst-case scenario for the incremental indexer, since
-    // each facet value contains only one document ID.
-    //
-    // In that scenario, it appears that the incremental indexer is about 70 times slower than the
-    // bulk indexer.
-    // #[test]
-    fn benchmark_facet_indexing_delete() {
-        let mut r = rand::thread_rng();
-
-        for i in 1..=20 {
-            let size = 50_000 * i;
-            let index = FacetIndex::<OrderedF64Codec>::new(4, 8, 5);
-
-            let mut txn = index.env.write_txn().unwrap();
-            let mut elements = Vec::<((u16, f64), RoaringBitmap)>::new();
-            for i in 0..size {
-                // field id = 0, left_bound = i, docids = [i]
-                elements.push(((0, i as f64), once(i).collect()));
-            }
-            let timer = std::time::Instant::now();
-            index.bulk_insert(&mut txn, &[0], elements.iter());
-            let time_spent = timer.elapsed().as_millis();
-            println!("bulk {size} : {time_spent}ms");
-
-            txn.commit().unwrap();
-
-            for nbr_doc in [1, 100, 1000, 10_000] {
-                let mut txn = index.env.write_txn().unwrap();
-                let timer = std::time::Instant::now();
-                //
-                // delete one document
-                //
-                for _ in 0..nbr_doc {
-                    let deleted_u32 = r.gen::<u32>() % size;
-                    let deleted_f64 = deleted_u32 as f64;
-                    index.delete_single_docid(&mut txn, 0, &deleted_f64, deleted_u32)
-                }
-                let time_spent = timer.elapsed().as_millis();
-                println!("    delete {nbr_doc} : {time_spent}ms");
-                txn.abort().unwrap();
-            }
-        }
-    }
-}

milli/src/update/facet/incremental.rs

@@ -1,9 +1,9 @@
-use std::collections::HashMap;
 use std::fs::File;
 use std::io::BufReader;
 
 use heed::types::{ByteSlice, DecodeIgnore};
 use heed::{BytesDecode, Error, RoTxn, RwTxn};
+use obkv::KvReader;
 use roaring::RoaringBitmap;
 
 use crate::facet::FacetType;
@@ -12,8 +12,9 @@ use crate::heed_codec::facet::{
 };
 use crate::heed_codec::ByteSliceRefCodec;
 use crate::search::facet::get_highest_level;
+use crate::update::del_add::DelAdd;
 use crate::update::index_documents::valid_lmdb_key;
-use crate::{CboRoaringBitmapCodec, FieldId, Index, Result};
+use crate::{CboRoaringBitmapCodec, Index, Result};
 
 enum InsertionResult {
     InPlace,
@@ -28,27 +29,21 @@ enum DeletionResult {
 
 /// Algorithm to incrementally insert and delete elememts into the
 /// `facet_id_(string/f64)_docids` databases.
-///
+pub struct FacetsUpdateIncremental {
-/// Rhe `faceted_documents_ids` value in the main database of `Index`
-/// is also updated to contain the new set of faceted documents.
-pub struct FacetsUpdateIncremental<'i> {
-    index: &'i Index,
     inner: FacetsUpdateIncrementalInner,
-    facet_type: FacetType,
+    delta_data: grenad::Reader<BufReader<File>>,
-    new_data: grenad::Reader<BufReader<File>>,
 }
 
-impl<'i> FacetsUpdateIncremental<'i> {
+impl FacetsUpdateIncremental {
     pub fn new(
-        index: &'i Index,
+        index: &Index,
         facet_type: FacetType,
-        new_data: grenad::Reader<BufReader<File>>,
+        delta_data: grenad::Reader<BufReader<File>>,
         group_size: u8,
         min_level_size: u8,
         max_group_size: u8,
     ) -> Self {
         FacetsUpdateIncremental {
-            index,
             inner: FacetsUpdateIncrementalInner {
                 db: match facet_type {
                     FacetType::String => index
@@ -62,31 +57,41 @@ impl<'i> FacetsUpdateIncremental<'i> {
                 max_group_size,
                 min_level_size,
             },
-            facet_type,
+            delta_data,
-            new_data,
         }
     }
 
-    pub fn execute(self, wtxn: &'i mut RwTxn) -> crate::Result<()> {
+    pub fn execute(self, wtxn: &mut RwTxn) -> crate::Result<()> {
-        let mut new_faceted_docids = HashMap::<FieldId, RoaringBitmap>::default();
+        let mut cursor = self.delta_data.into_cursor()?;
-
-        let mut cursor = self.new_data.into_cursor()?;
         while let Some((key, value)) = cursor.move_on_next()? {
             if !valid_lmdb_key(key) {
                 continue;
             }
             let key = FacetGroupKeyCodec::<ByteSliceRefCodec>::bytes_decode(key)
                 .ok_or(heed::Error::Encoding)?;
-            let docids = CboRoaringBitmapCodec::bytes_decode(value).ok_or(heed::Error::Encoding)?;
+            let value = KvReader::new(value);
-            self.inner.insert(wtxn, key.field_id, key.left_bound, &docids)?;
+
-            *new_faceted_docids.entry(key.field_id).or_default() |= docids;
+            let docids_to_delete = value
+                .get(DelAdd::Deletion)
+                .map(CboRoaringBitmapCodec::bytes_decode)
+                .map(|o| o.ok_or(heed::Error::Encoding));
+
+            let docids_to_add = value
+                .get(DelAdd::Addition)
+                .map(CboRoaringBitmapCodec::bytes_decode)
+                .map(|o| o.ok_or(heed::Error::Encoding));
+
+            if let Some(docids_to_delete) = docids_to_delete {
+                let docids_to_delete = docids_to_delete?;
+                self.inner.delete(wtxn, key.field_id, key.left_bound, &docids_to_delete)?;
+            }
+
+            if let Some(docids_to_add) = docids_to_add {
+                let docids_to_add = docids_to_add?;
+                self.inner.insert(wtxn, key.field_id, key.left_bound, &docids_to_add)?;
+            }
         }
 
-        for (field_id, new_docids) in new_faceted_docids {
-            let mut docids = self.index.faceted_documents_ids(wtxn, field_id, self.facet_type)?;
-            docids |= new_docids;
-            self.index.put_faceted_documents_ids(wtxn, field_id, self.facet_type, &docids)?;
-        }
         Ok(())
     }
 }

milli/src/update/facet/mod.rs

@@ -14,7 +14,7 @@ The databases must be able to return results for queries such as:
 The algorithms that implement these queries are found in the `src/search/facet` folder.
 
 To make these queries fast to compute, the database adopts a tree structure:
-```ignore
+```text
             ┌───────────────────────────────┬───────────────────────────────┬───────────────┐
 ┌───────┐   │           "ab" (2)            │           "gaf" (2)           │   "woz" (1)   │
 │Level 2│   │                               │                               │               │
@@ -41,7 +41,7 @@ These documents all contain a facet value that is contained within `ab .. gaf`.
 In the database, each node is represented by a key/value pair encoded as a [`FacetGroupKey`] and a
 [`FacetGroupValue`], which have the following format:
 
-```ignore
+```text
 FacetGroupKey:
 - field id  : u16
 - level     : u8
@@ -98,7 +98,6 @@ use crate::update::merge_btreeset_string;
 use crate::{BEU16StrCodec, Index, Result, BEU16, MAX_FACET_VALUE_LENGTH};
 
 pub mod bulk;
-pub mod delete;
 pub mod incremental;
 
 /// A builder used to add new elements to the `facet_id_string_docids` or `facet_id_f64_docids` databases.
@@ -109,7 +108,7 @@ pub struct FacetsUpdate<'i> {
     index: &'i Index,
     database: heed::Database<FacetGroupKeyCodec<ByteSliceRefCodec>, FacetGroupValueCodec>,
     facet_type: FacetType,
-    new_data: grenad::Reader<BufReader<File>>,
+    delta_data: grenad::Reader<BufReader<File>>,
     group_size: u8,
     max_group_size: u8,
     min_level_size: u8,
@@ -118,7 +117,7 @@ impl<'i> FacetsUpdate<'i> {
     pub fn new(
         index: &'i Index,
         facet_type: FacetType,
-        new_data: grenad::Reader<BufReader<File>>,
+        delta_data: grenad::Reader<BufReader<File>>,
     ) -> Self {
         let database = match facet_type {
             FacetType::String => index
@@ -135,26 +134,26 @@ impl<'i> FacetsUpdate<'i> {
             max_group_size: FACET_MAX_GROUP_SIZE,
             min_level_size: FACET_MIN_LEVEL_SIZE,
             facet_type,
-            new_data,
+            delta_data,
         }
     }
 
     pub fn execute(self, wtxn: &mut heed::RwTxn) -> Result<()> {
-        if self.new_data.is_empty() {
+        if self.delta_data.is_empty() {
             return Ok(());
         }
         debug!("Computing and writing the facet values levels docids into LMDB on disk...");
         self.index.set_updated_at(wtxn, &OffsetDateTime::now_utc())?;
 
         // See self::comparison_bench::benchmark_facet_indexing
-        if self.new_data.len() >= (self.database.len(wtxn)? as u64 / 50) {
+        if self.delta_data.len() >= (self.database.len(wtxn)? as u64 / 50) {
             let field_ids =
                 self.index.faceted_fields_ids(wtxn)?.iter().copied().collect::<Vec<_>>();
             let bulk_update = FacetsUpdateBulk::new(
                 self.index,
                 field_ids,
                 self.facet_type,
-                self.new_data,
+                self.delta_data,
                 self.group_size,
                 self.min_level_size,
             );
@@ -163,7 +162,7 @@ impl<'i> FacetsUpdate<'i> {
             let incremental_update = FacetsUpdateIncremental::new(
                 self.index,
                 self.facet_type,
-                self.new_data,
+                self.delta_data,
                 self.group_size,
                 self.min_level_size,
                 self.max_group_size,
@@ -279,6 +278,7 @@ pub(crate) mod test_helpers {
     use crate::heed_codec::ByteSliceRefCodec;
     use crate::search::facet::get_highest_level;
     use crate::snapshot_tests::display_bitmap;
+    use crate::update::del_add::{DelAdd, KvWriterDelAdd};
     use crate::update::FacetsUpdateIncrementalInner;
     use crate::CboRoaringBitmapCodec;
 
@@ -455,20 +455,22 @@ pub(crate) mod test_helpers {
                 let key: FacetGroupKey<&[u8]> =
                     FacetGroupKey { field_id: *field_id, level: 0, left_bound: &left_bound_bytes };
                 let key = FacetGroupKeyCodec::<ByteSliceRefCodec>::bytes_encode(&key).unwrap();
+                let mut inner_writer = KvWriterDelAdd::memory();
                 let value = CboRoaringBitmapCodec::bytes_encode(docids).unwrap();
-                writer.insert(&key, &value).unwrap();
+                inner_writer.insert(DelAdd::Addition, value).unwrap();
+                writer.insert(&key, inner_writer.into_inner().unwrap()).unwrap();
             }
             writer.finish().unwrap();
             let reader = grenad::Reader::new(std::io::Cursor::new(new_data)).unwrap();
 
             let update = FacetsUpdateBulkInner {
                 db: self.content,
-                new_data: Some(reader),
+                delta_data: Some(reader),
                 group_size: self.group_size.get(),
                 min_level_size: self.min_level_size.get(),
             };
 
-            update.update(wtxn, field_ids, |_, _, _| Ok(())).unwrap();
+            update.update(wtxn, field_ids).unwrap();
         }
 
         pub fn verify_structure_validity(&self, txn: &RoTxn, field_id: u16) {
@@ -556,101 +558,6 @@ pub(crate) mod test_helpers {
     }
 }
 
-#[cfg(test)]
-mod tests {
-    use big_s::S;
-    use maplit::hashset;
-
-    use crate::db_snap;
-    use crate::documents::documents_batch_reader_from_objects;
-    use crate::index::tests::TempIndex;
-    use crate::update::DeletionStrategy;
-
-    #[test]
-    fn replace_all_identical_soft_deletion_then_hard_deletion() {
-        let mut index = TempIndex::new_with_map_size(4096 * 1000 * 100);
-
-        index.index_documents_config.deletion_strategy = DeletionStrategy::AlwaysSoft;
-
-        index
-            .update_settings(|settings| {
-                settings.set_primary_key("id".to_owned());
-                settings.set_filterable_fields(hashset! { S("size") });
-            })
-            .unwrap();
-
-        let mut documents = vec![];
-        for i in 0..1000 {
-            documents.push(
-                serde_json::json! {
-                    {
-                        "id": i,
-                        "size": i % 250,
-                    }
-                }
-                .as_object()
-                .unwrap()
-                .clone(),
-            );
-        }
-
-        let documents = documents_batch_reader_from_objects(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, facet_id_f64_docids, "initial", @"777e0e221d778764b472c512617eeb3b");
-        db_snap!(index, number_faceted_documents_ids, "initial", @"bd916ef32b05fd5c3c4c518708f431a9");
-        db_snap!(index, soft_deleted_documents_ids, "initial", @"[]");
-
-        let mut documents = vec![];
-        for i in 0..999 {
-            documents.push(
-                serde_json::json! {
-                    {
-                        "id": i,
-                        "size": i % 250,
-                        "other": 0,
-                    }
-                }
-                .as_object()
-                .unwrap()
-                .clone(),
-            );
-        }
-
-        let documents = documents_batch_reader_from_objects(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, facet_id_f64_docids, "replaced_1_soft", @"abba175d7bed727d0efadaef85a4388f");
-        db_snap!(index, number_faceted_documents_ids, "replaced_1_soft", @"de76488bd05ad94c6452d725acf1bd06");
-        db_snap!(index, soft_deleted_documents_ids, "replaced_1_soft", @"6c975deb900f286d2f6456d2d5c3a123");
-
-        // Then replace the last document while disabling soft_deletion
-        index.index_documents_config.deletion_strategy = DeletionStrategy::AlwaysHard;
-        let mut documents = vec![];
-        for i in 999..1000 {
-            documents.push(
-                serde_json::json! {
-                    {
-                        "id": i,
-                        "size": i % 250,
-                        "other": 0,
-                    }
-                }
-                .as_object()
-                .unwrap()
-                .clone(),
-            );
-        }
-
-        let documents = documents_batch_reader_from_objects(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, facet_id_f64_docids, "replaced_2_hard", @"029e27a46d09c574ae949aa4289b45e6");
-        db_snap!(index, number_faceted_documents_ids, "replaced_2_hard", @"60b19824f136affe6b240a7200779028");
-        db_snap!(index, soft_deleted_documents_ids, "replaced_2_hard", @"[]");
-    }
-}
-
 #[allow(unused)]
 #[cfg(test)]
 mod comparison_bench {

milli/src/update/index_documents/enrich.rs

@@ -1,20 +1,17 @@
+use std::fmt;
 use std::io::{BufWriter, Read, Seek};
 use std::result::Result as StdResult;
-use std::{fmt, iter};
 
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
-use crate::documents::{DocumentsBatchIndex, DocumentsBatchReader, EnrichedDocumentsBatchReader};
+use crate::documents::{
+    DocumentIdExtractionError, DocumentsBatchIndex, DocumentsBatchReader,
+    EnrichedDocumentsBatchReader, PrimaryKey, DEFAULT_PRIMARY_KEY,
+};
 use crate::error::{GeoError, InternalError, UserError};
 use crate::update::index_documents::{obkv_to_object, writer_into_reader};
-use crate::{FieldId, Index, Object, Result};
+use crate::{FieldId, Index, Result};
-
-/// The symbol used to define levels in a nested primary key.
-const PRIMARY_KEY_SPLIT_SYMBOL: char = '.';
-
-/// The default primary that is used when not specified.
-const DEFAULT_PRIMARY_KEY: &str = "id";
 
 /// This function validates and enrich the documents by checking that:
 ///  - we can infer a primary key,
@@ -41,14 +38,12 @@ pub fn enrich_documents_batch<R: Read + Seek>(
     // The primary key *field id* that has already been set for this index or the one
     // we will guess by searching for the first key that contains "id" as a substring.
     let primary_key = match index.primary_key(rtxn)? {
-        Some(primary_key) if primary_key.contains(PRIMARY_KEY_SPLIT_SYMBOL) => {
+        Some(primary_key) => match PrimaryKey::new(primary_key, &documents_batch_index) {
-            PrimaryKey::nested(primary_key)
+            Some(primary_key) => primary_key,
-        }
+            None if autogenerate_docids => PrimaryKey::Flat {
-        Some(primary_key) => match documents_batch_index.id(primary_key) {
+                name: primary_key,
-            Some(id) => PrimaryKey::flat(primary_key, id),
+                field_id: documents_batch_index.insert(primary_key),
-            None if autogenerate_docids => {
+            },
-                PrimaryKey::flat(primary_key, documents_batch_index.insert(primary_key))
-            }
             None => {
                 return match cursor.next_document()? {
                     Some(first_document) => Ok(Err(UserError::MissingDocumentId {
@@ -76,14 +71,14 @@ pub fn enrich_documents_batch<R: Read + Seek>(
             });
 
             match guesses.as_slice() {
-                [] if autogenerate_docids => PrimaryKey::flat(
+                [] if autogenerate_docids => PrimaryKey::Flat {
-                    DEFAULT_PRIMARY_KEY,
+                    name: DEFAULT_PRIMARY_KEY,
-                    documents_batch_index.insert(DEFAULT_PRIMARY_KEY),
+                    field_id: documents_batch_index.insert(DEFAULT_PRIMARY_KEY),
-                ),
+                },
                 [] => return Ok(Err(UserError::NoPrimaryKeyCandidateFound)),
                 [(field_id, name)] => {
                     log::info!("Primary key was not specified in index. Inferred to '{name}'");
-                    PrimaryKey::flat(name, *field_id)
+                    PrimaryKey::Flat { name, field_id: *field_id }
                 }
                 multiple => {
                     return Ok(Err(UserError::MultiplePrimaryKeyCandidatesFound {
@@ -156,92 +151,24 @@ fn fetch_or_generate_document_id(
     uuid_buffer: &mut [u8; uuid::fmt::Hyphenated::LENGTH],
     count: u32,
 ) -> Result<StdResult<DocumentId, UserError>> {
-    match primary_key {
+    Ok(match primary_key.document_id(document, documents_batch_index)? {
-        PrimaryKey::Flat { name: primary_key, field_id: primary_key_id } => {
+        Ok(document_id) => Ok(DocumentId::Retrieved { value: document_id }),
-            match document.get(primary_key_id) {
+        Err(DocumentIdExtractionError::InvalidDocumentId(user_error)) => Err(user_error),
-                Some(document_id_bytes) => {
+        Err(DocumentIdExtractionError::MissingDocumentId) if autogenerate_docids => {
-                    let document_id = serde_json::from_slice(document_id_bytes)
+            let uuid = uuid::Uuid::new_v4().as_hyphenated().encode_lower(uuid_buffer);
-                        .map_err(InternalError::SerdeJson)?;
+            Ok(DocumentId::Generated { value: uuid.to_string(), document_nth: count })
-                    match validate_document_id_value(document_id)? {
-                        Ok(document_id) => Ok(Ok(DocumentId::retrieved(document_id))),
-                        Err(user_error) => Ok(Err(user_error)),
-                    }
-                }
-                None if autogenerate_docids => {
-                    let uuid = uuid::Uuid::new_v4().as_hyphenated().encode_lower(uuid_buffer);
-                    Ok(Ok(DocumentId::generated(uuid.to_string(), count)))
-                }
-                None => Ok(Err(UserError::MissingDocumentId {
-                    primary_key: primary_key.to_string(),
-                    document: obkv_to_object(document, documents_batch_index)?,
-                })),
-            }
         }
-        nested @ PrimaryKey::Nested { .. } => {
+        Err(DocumentIdExtractionError::MissingDocumentId) => Err(UserError::MissingDocumentId {
-            let mut matching_documents_ids = Vec::new();
+            primary_key: primary_key.name().to_string(),
-            for (first_level_name, right) in nested.possible_level_names() {
+            document: obkv_to_object(document, documents_batch_index)?,
-                if let Some(field_id) = documents_batch_index.id(first_level_name) {
+        }),
-                    if let Some(value_bytes) = document.get(field_id) {
+        Err(DocumentIdExtractionError::TooManyDocumentIds(_)) => {
-                        let object = serde_json::from_slice(value_bytes)
+            Err(UserError::TooManyDocumentIds {
-                            .map_err(InternalError::SerdeJson)?;
+                primary_key: primary_key.name().to_string(),
-                        fetch_matching_values(object, right, &mut matching_documents_ids);
+                document: obkv_to_object(document, documents_batch_index)?,
-
+            })
-                        if matching_documents_ids.len() >= 2 {
-                            return Ok(Err(UserError::TooManyDocumentIds {
-                                primary_key: nested.name().to_string(),
-                                document: obkv_to_object(document, documents_batch_index)?,
-                            }));
-                        }
-                    }
-                }
-            }
-
-            match matching_documents_ids.pop() {
-                Some(document_id) => match validate_document_id_value(document_id)? {
-                    Ok(document_id) => Ok(Ok(DocumentId::retrieved(document_id))),
-                    Err(user_error) => Ok(Err(user_error)),
-                },
-                None => Ok(Err(UserError::MissingDocumentId {
-                    primary_key: nested.name().to_string(),
-                    document: obkv_to_object(document, documents_batch_index)?,
-                })),
-            }
         }
-    }
+    })
-}
-
-/// A type that represent the type of primary key that has been set
-/// for this index, a classic flat one or a nested one.
-#[derive(Debug, Clone, Copy)]
-enum PrimaryKey<'a> {
-    Flat { name: &'a str, field_id: FieldId },
-    Nested { name: &'a str },
-}
-
-impl PrimaryKey<'_> {
-    fn flat(name: &str, field_id: FieldId) -> PrimaryKey {
-        PrimaryKey::Flat { name, field_id }
-    }
-
-    fn nested(name: &str) -> PrimaryKey {
-        PrimaryKey::Nested { name }
-    }
-
-    fn name(&self) -> &str {
-        match self {
-            PrimaryKey::Flat { name, .. } => name,
-            PrimaryKey::Nested { name } => name,
-        }
-    }
-
-    /// Returns an `Iterator` that gives all the possible fields names the primary key
-    /// can have depending of the first level name and deepnes of the objects.
-    fn possible_level_names(&self) -> impl Iterator<Item = (&str, &str)> + '_ {
-        let name = self.name();
-        name.match_indices(PRIMARY_KEY_SPLIT_SYMBOL)
-            .map(move |(i, _)| (&name[..i], &name[i + PRIMARY_KEY_SPLIT_SYMBOL.len_utf8()..]))
-            .chain(iter::once((name, "")))
-    }
 }
 
 /// A type that represents a document id that has been retrieved from a document or auto-generated.
@@ -255,14 +182,6 @@ pub enum DocumentId {
 }
 
 impl DocumentId {
-    fn retrieved(value: String) -> DocumentId {
-        DocumentId::Retrieved { value }
-    }
-
-    fn generated(value: String, document_nth: u32) -> DocumentId {
-        DocumentId::Generated { value, document_nth }
-    }
-
     fn debug(&self) -> String {
         format!("{:?}", self)
     }
@@ -290,66 +209,6 @@ impl fmt::Debug for DocumentId {
     }
 }
 
-fn starts_with(selector: &str, key: &str) -> bool {
-    selector.strip_prefix(key).map_or(false, |tail| {
-        tail.chars().next().map(|c| c == PRIMARY_KEY_SPLIT_SYMBOL).unwrap_or(true)
-    })
-}
-
-pub fn fetch_matching_values(value: Value, selector: &str, output: &mut Vec<Value>) {
-    match value {
-        Value::Object(object) => fetch_matching_values_in_object(object, selector, "", output),
-        otherwise => output.push(otherwise),
-    }
-}
-
-pub fn fetch_matching_values_in_object(
-    object: Object,
-    selector: &str,
-    base_key: &str,
-    output: &mut Vec<Value>,
-) {
-    for (key, value) in object {
-        let base_key = if base_key.is_empty() {
-            key.to_string()
-        } else {
-            format!("{}{}{}", base_key, PRIMARY_KEY_SPLIT_SYMBOL, key)
-        };
-
-        if starts_with(selector, &base_key) {
-            match value {
-                Value::Object(object) => {
-                    fetch_matching_values_in_object(object, selector, &base_key, output)
-                }
-                value => output.push(value),
-            }
-        }
-    }
-}
-
-pub fn validate_document_id(document_id: &str) -> Option<&str> {
-    if !document_id.is_empty()
-        && document_id.chars().all(|c| matches!(c, 'a'..='z' | 'A'..='Z' | '0'..='9' | '-' | '_'))
-    {
-        Some(document_id)
-    } else {
-        None
-    }
-}
-
-/// Parses a Json encoded document id and validate it, returning a user error when it is one.
-pub fn validate_document_id_value(document_id: Value) -> Result<StdResult<String, UserError>> {
-    match document_id {
-        Value::String(string) => match validate_document_id(&string) {
-            Some(s) if s.len() == string.len() => Ok(Ok(string)),
-            Some(s) => Ok(Ok(s.to_string())),
-            None => Ok(Err(UserError::InvalidDocumentId { document_id: Value::String(string) })),
-        },
-        Value::Number(number) if number.is_i64() => Ok(Ok(number.to_string())),
-        content => Ok(Err(UserError::InvalidDocumentId { document_id: content })),
-    }
-}
-
 /// Try to extract an `f64` from a JSON `Value` and return the `Value`
 /// in the `Err` variant if it failed.
 pub fn extract_finite_float_from_value(value: Value) -> StdResult<f64, Value> {

milli/src/update/index_documents/extract/extract_docid_word_positions.rs

@@ -5,18 +5,16 @@ use std::io::BufReader;
 use std::{io, mem, str};
 
 use charabia::{Language, Script, SeparatorKind, Token, TokenKind, Tokenizer, TokenizerBuilder};
-use obkv::KvReader;
+use obkv::{KvReader, KvWriterU16};
 use roaring::RoaringBitmap;
 use serde_json::Value;
 
-use super::helpers::{concat_u32s_array, create_sorter, sorter_into_reader, GrenadParameters};
+use super::helpers::{create_sorter, keep_latest_obkv, sorter_into_reader, GrenadParameters};
 use crate::error::{InternalError, SerializationError};
-use crate::update::index_documents::MergeFn;
+use crate::update::del_add::{del_add_from_two_obkvs, DelAdd, KvReaderDelAdd};
-use crate::{
+use crate::{FieldId, Result, MAX_POSITION_PER_ATTRIBUTE, MAX_WORD_LENGTH};
-    absolute_from_relative_position, FieldId, Result, MAX_POSITION_PER_ATTRIBUTE, MAX_WORD_LENGTH,
-};
 
-pub type ScriptLanguageDocidsMap = HashMap<(Script, Language), RoaringBitmap>;
+pub type ScriptLanguageDocidsMap = HashMap<(Script, Language), (RoaringBitmap, RoaringBitmap)>;
 
 /// Extracts the word and positions where this word appear and
 /// prefixes it by the document id.
@@ -32,25 +30,162 @@ pub fn extract_docid_word_positions<R: io::Read + io::Seek>(
     allowed_separators: Option<&[&str]>,
     dictionary: Option<&[&str]>,
     max_positions_per_attributes: Option<u32>,
-) -> Result<(RoaringBitmap, grenad::Reader<BufReader<File>>, ScriptLanguageDocidsMap)> {
+) -> Result<(grenad::Reader<BufReader<File>>, ScriptLanguageDocidsMap)> {
     puffin::profile_function!();
 
     let max_positions_per_attributes = max_positions_per_attributes
         .map_or(MAX_POSITION_PER_ATTRIBUTE, |max| max.min(MAX_POSITION_PER_ATTRIBUTE));
     let max_memory = indexer.max_memory_by_thread();
 
+    // initialize destination values.
     let mut documents_ids = RoaringBitmap::new();
     let mut script_language_docids = HashMap::new();
     let mut docid_word_positions_sorter = create_sorter(
         grenad::SortAlgorithm::Stable,
-        concat_u32s_array,
+        keep_latest_obkv,
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
         indexer.max_nb_chunks,
         max_memory,
     );
 
-    let mut buffers = Buffers::default();
+    // initialize buffers.
+    let mut del_buffers = Buffers::default();
+    let mut add_buffers = Buffers::default();
+    let mut key_buffer = Vec::new();
+    let mut value_buffer = Vec::new();
+
+    // initialize tokenizer.
+    let mut builder = tokenizer_builder(stop_words, allowed_separators, dictionary, None);
+    let tokenizer = builder.build();
+
+    // iterate over documents.
+    let mut cursor = obkv_documents.into_cursor()?;
+    while let Some((key, value)) = cursor.move_on_next()? {
+        let document_id = key
+            .try_into()
+            .map(u32::from_be_bytes)
+            .map_err(|_| SerializationError::InvalidNumberSerialization)?;
+        let obkv = KvReader::<FieldId>::new(value);
+
+        // if the searchable fields didn't change, skip the searchable indexing for this document.
+        if !searchable_fields_changed(&KvReader::<FieldId>::new(value), searchable_fields) {
+            continue;
+        }
+
+        documents_ids.push(document_id);
+
+        // Update key buffer prefix.
+        key_buffer.clear();
+        key_buffer.extend_from_slice(&document_id.to_be_bytes());
+
+        // Tokenize deletions and additions in 2 diffferent threads.
+        let (del, add): (Result<_>, Result<_>) = rayon::join(
+            || {
+                // deletions
+                lang_safe_tokens_from_document(
+                    &obkv,
+                    searchable_fields,
+                    &tokenizer,
+                    stop_words,
+                    allowed_separators,
+                    dictionary,
+                    max_positions_per_attributes,
+                    DelAdd::Deletion,
+                    &mut del_buffers,
+                )
+            },
+            || {
+                // additions
+                lang_safe_tokens_from_document(
+                    &obkv,
+                    searchable_fields,
+                    &tokenizer,
+                    stop_words,
+                    allowed_separators,
+                    dictionary,
+                    max_positions_per_attributes,
+                    DelAdd::Addition,
+                    &mut add_buffers,
+                )
+            },
+        );
+
+        let (del_obkv, del_script_language_word_count) = del?;
+        let (add_obkv, add_script_language_word_count) = add?;
+
+        // merge deletions and additions.
+        // transforming two KV<FieldId, KV<u16, String>> into one KV<FieldId, KV<DelAdd, KV<u16, String>>>
+        value_buffer.clear();
+        del_add_from_two_obkvs(
+            KvReader::<FieldId>::new(del_obkv),
+            KvReader::<FieldId>::new(add_obkv),
+            &mut value_buffer,
+        )?;
+
+        // write each KV<DelAdd, KV<u16, String>> into the sorter, field by field.
+        let obkv = KvReader::<FieldId>::new(&value_buffer);
+        for (field_id, value) in obkv.iter() {
+            key_buffer.truncate(mem::size_of::<u32>());
+            key_buffer.extend_from_slice(&field_id.to_be_bytes());
+            docid_word_positions_sorter.insert(&key_buffer, value)?;
+        }
+
+        // update script_language_docids deletions.
+        for (script, languages_frequency) in del_script_language_word_count {
+            for (language, _) in languages_frequency {
+                let entry = script_language_docids
+                    .entry((script, language))
+                    .or_insert_with(|| (RoaringBitmap::new(), RoaringBitmap::new()));
+                entry.0.push(document_id);
+            }
+        }
+
+        // update script_language_docids additions.
+        for (script, languages_frequency) in add_script_language_word_count {
+            for (language, _) in languages_frequency {
+                let entry = script_language_docids
+                    .entry((script, language))
+                    .or_insert_with(|| (RoaringBitmap::new(), RoaringBitmap::new()));
+                entry.1.push(document_id);
+            }
+        }
+    }
+
+    // the returned sorter is serialized as: key: (DocId, FieldId), value: KV<DelAdd, KV<u16, String>>.
+    sorter_into_reader(docid_word_positions_sorter, indexer)
+        .map(|reader| (reader, script_language_docids))
+}
+
+/// Check if any searchable fields of a document changed.
+fn searchable_fields_changed(
+    obkv: &KvReader<FieldId>,
+    searchable_fields: &Option<HashSet<FieldId>>,
+) -> bool {
+    for (field_id, field_bytes) in obkv.iter() {
+        if searchable_fields.as_ref().map_or(true, |sf| sf.contains(&field_id)) {
+            let del_add = KvReaderDelAdd::new(field_bytes);
+            match (del_add.get(DelAdd::Deletion), del_add.get(DelAdd::Addition)) {
+                // if both fields are None, check the next field.
+                (None, None) => (),
+                // if both contains a value and values are the same, check the next field.
+                (Some(del), Some(add)) if del == add => (),
+                // otherwise the fields are different, return true.
+                _otherwise => return true,
+            }
+        }
+    }
+
+    false
+}
+
+/// Factorize tokenizer building.
+fn tokenizer_builder<'a>(
+    stop_words: Option<&'a fst::Set<&[u8]>>,
+    allowed_separators: Option<&'a [&str]>,
+    dictionary: Option<&'a [&str]>,
+    script_language: Option<&'a HashMap<Script, Vec<Language>>>,
+) -> TokenizerBuilder<'a, &'a [u8]> {
     let mut tokenizer_builder = TokenizerBuilder::new();
     if let Some(stop_words) = stop_words {
         tokenizer_builder.stop_words(stop_words);
@@ -61,130 +196,147 @@ pub fn extract_docid_word_positions<R: io::Read + io::Seek>(
     if let Some(separators) = allowed_separators {
         tokenizer_builder.separators(separators);
     }
-    let tokenizer = tokenizer_builder.build();
 
-    let mut cursor = obkv_documents.into_cursor()?;
+    if let Some(script_language) = script_language {
-    while let Some((key, value)) = cursor.move_on_next()? {
+        tokenizer_builder.allow_list(script_language);
-        let document_id = key
+    }
-            .try_into()
-            .map(u32::from_be_bytes)
-            .map_err(|_| SerializationError::InvalidNumberSerialization)?;
-        let obkv = KvReader::<FieldId>::new(value);
 
-        documents_ids.push(document_id);
+    tokenizer_builder
-        buffers.key_buffer.clear();
+}
-        buffers.key_buffer.extend_from_slice(&document_id.to_be_bytes());
 
-        let mut script_language_word_count = HashMap::new();
+/// Extract words mapped with their positions of a document,
+/// ensuring no Language detection mistakes was made.
+#[allow(clippy::too_many_arguments)] // FIXME: consider grouping arguments in a struct
+fn lang_safe_tokens_from_document<'a>(
+    obkv: &KvReader<FieldId>,
+    searchable_fields: &Option<HashSet<FieldId>>,
+    tokenizer: &Tokenizer,
+    stop_words: Option<&fst::Set<&[u8]>>,
+    allowed_separators: Option<&[&str]>,
+    dictionary: Option<&[&str]>,
+    max_positions_per_attributes: u32,
+    del_add: DelAdd,
+    buffers: &'a mut Buffers,
+) -> Result<(&'a [u8], HashMap<Script, Vec<(Language, usize)>>)> {
+    let mut script_language_word_count = HashMap::new();
 
-        extract_tokens_from_document(
+    tokens_from_document(
-            &obkv,
+        obkv,
-            searchable_fields,
+        searchable_fields,
-            &tokenizer,
+        tokenizer,
-            max_positions_per_attributes,
+        max_positions_per_attributes,
-            &mut buffers,
+        del_add,
-            &mut script_language_word_count,
+        buffers,
-            &mut docid_word_positions_sorter,
+        &mut script_language_word_count,
-        )?;
+    )?;
 
-        // if we detect a potetial mistake in the language detection,
+    // if we detect a potetial mistake in the language detection,
-        // we rerun the extraction forcing the tokenizer to detect the most frequently detected Languages.
+    // we rerun the extraction forcing the tokenizer to detect the most frequently detected Languages.
-        // context: https://github.com/meilisearch/meilisearch/issues/3565
+    // context: https://github.com/meilisearch/meilisearch/issues/3565
-        if script_language_word_count
+    if script_language_word_count
-            .values()
+        .values()
-            .map(Vec::as_slice)
+        .map(Vec::as_slice)
-            .any(potential_language_detection_error)
+        .any(potential_language_detection_error)
-        {
+    {
-            // build an allow list with the most frequent detected languages in the document.
+        // build an allow list with the most frequent detected languages in the document.
-            let script_language: HashMap<_, _> =
+        let script_language: HashMap<_, _> =
-                script_language_word_count.iter().filter_map(most_frequent_languages).collect();
+            script_language_word_count.iter().filter_map(most_frequent_languages).collect();
 
-            // if the allow list is empty, meaning that no Language is considered frequent,
+        // if the allow list is empty, meaning that no Language is considered frequent,
-            // then we don't rerun the extraction.
+        // then we don't rerun the extraction.
-            if !script_language.is_empty() {
+        if !script_language.is_empty() {
-                // build a new temporary tokenizer including the allow list.
+            // build a new temporary tokenizer including the allow list.
-                let mut tokenizer_builder = TokenizerBuilder::new();
+            let mut builder = tokenizer_builder(
-                if let Some(stop_words) = stop_words {
+                stop_words,
-                    tokenizer_builder.stop_words(stop_words);
+                allowed_separators,
-                }
+                dictionary,
-                tokenizer_builder.allow_list(&script_language);
+                Some(&script_language),
-                let tokenizer = tokenizer_builder.build();
+            );
+            let tokenizer = builder.build();
 
-                script_language_word_count.clear();
+            script_language_word_count.clear();
 
-                // rerun the extraction.
+            // rerun the extraction.
-                extract_tokens_from_document(
+            tokens_from_document(
-                    &obkv,
+                obkv,
-                    searchable_fields,
+                searchable_fields,
-                    &tokenizer,
+                &tokenizer,
-                    max_positions_per_attributes,
+                max_positions_per_attributes,
-                    &mut buffers,
+                del_add,
-                    &mut script_language_word_count,
+                buffers,
-                    &mut docid_word_positions_sorter,
+                &mut script_language_word_count,
-                )?;
+            )?;
-            }
-        }
-
-        for (script, languages_frequency) in script_language_word_count {
-            for (language, _) in languages_frequency {
-                let entry = script_language_docids
-                    .entry((script, language))
-                    .or_insert_with(RoaringBitmap::new);
-                entry.push(document_id);
-            }
         }
     }
 
-    sorter_into_reader(docid_word_positions_sorter, indexer)
+    // returns a (KV<FieldId, KV<u16, String>>, HashMap<Script, Vec<(Language, usize)>>)
-        .map(|reader| (documents_ids, reader, script_language_docids))
+    Ok((&buffers.obkv_buffer, script_language_word_count))
 }
 
-fn extract_tokens_from_document(
+/// Extract words mapped with their positions of a document.
+fn tokens_from_document<'a>(
     obkv: &KvReader<FieldId>,
     searchable_fields: &Option<HashSet<FieldId>>,
     tokenizer: &Tokenizer,
     max_positions_per_attributes: u32,
-    buffers: &mut Buffers,
+    del_add: DelAdd,
+    buffers: &'a mut Buffers,
     script_language_word_count: &mut HashMap<Script, Vec<(Language, usize)>>,
-    docid_word_positions_sorter: &mut grenad::Sorter<MergeFn>,
+) -> Result<&'a [u8]> {
-) -> Result<()> {
+    buffers.obkv_buffer.clear();
+    let mut document_writer = KvWriterU16::new(&mut buffers.obkv_buffer);
     for (field_id, field_bytes) in obkv.iter() {
+        // if field is searchable.
         if searchable_fields.as_ref().map_or(true, |sf| sf.contains(&field_id)) {
-            let value = serde_json::from_slice(field_bytes).map_err(InternalError::SerdeJson)?;
+            // extract deletion or addition only.
-            buffers.field_buffer.clear();
+            if let Some(field_bytes) = KvReaderDelAdd::new(field_bytes).get(del_add) {
-            if let Some(field) = json_to_string(&value, &mut buffers.field_buffer) {
+                // parse json.
-                let tokens = process_tokens(tokenizer.tokenize(field))
+                let value =
-                    .take_while(|(p, _)| (*p as u32) < max_positions_per_attributes);
+                    serde_json::from_slice(field_bytes).map_err(InternalError::SerdeJson)?;
 
-                for (index, token) in tokens {
+                // prepare writing destination.
-                    // if a language has been detected for the token, we update the counter.
+                buffers.obkv_positions_buffer.clear();
-                    if let Some(language) = token.language {
+                let mut writer = KvWriterU16::new(&mut buffers.obkv_positions_buffer);
-                        let script = token.script;
+
-                        let entry =
+                // convert json into a unique string.
-                            script_language_word_count.entry(script).or_insert_with(Vec::new);
+                buffers.field_buffer.clear();
-                        match entry.iter_mut().find(|(l, _)| *l == language) {
+                if let Some(field) = json_to_string(&value, &mut buffers.field_buffer) {
-                            Some((_, n)) => *n += 1,
+                    // create an iterator of token with their positions.
-                            None => entry.push((language, 1)),
+                    let tokens = process_tokens(tokenizer.tokenize(field))
+                        .take_while(|(p, _)| (*p as u32) < max_positions_per_attributes);
+
+                    for (index, token) in tokens {
+                        // if a language has been detected for the token, we update the counter.
+                        if let Some(language) = token.language {
+                            let script = token.script;
+                            let entry =
+                                script_language_word_count.entry(script).or_insert_with(Vec::new);
+                            match entry.iter_mut().find(|(l, _)| *l == language) {
+                                Some((_, n)) => *n += 1,
+                                None => entry.push((language, 1)),
+                            }
+                        }
+
+                        // keep a word only if it is not empty and fit in a LMDB key.
+                        let token = token.lemma().trim();
+                        if !token.is_empty() && token.len() <= MAX_WORD_LENGTH {
+                            let position: u16 = index
+                                .try_into()
+                                .map_err(|_| SerializationError::InvalidNumberSerialization)?;
+                            writer.insert(position, token.as_bytes())?;
                         }
                     }
-                    let token = token.lemma().trim();
-                    if !token.is_empty() && token.len() <= MAX_WORD_LENGTH {
-                        buffers.key_buffer.truncate(mem::size_of::<u32>());
-                        buffers.key_buffer.extend_from_slice(token.as_bytes());
 
-                        let position: u16 = index
+                    // write positions into document.
-                            .try_into()
+                    let positions = writer.into_inner()?;
-                            .map_err(|_| SerializationError::InvalidNumberSerialization)?;
+                    document_writer.insert(field_id, positions)?;
-                        let position = absolute_from_relative_position(field_id, position);
-                        docid_word_positions_sorter
-                            .insert(&buffers.key_buffer, position.to_ne_bytes())?;
-                    }
                 }
             }
         }
     }
 
-    Ok(())
+    // returns a KV<FieldId, KV<u16, String>>
+    Ok(document_writer.into_inner().map(|v| v.as_slice())?)
 }
 
 /// Transform a JSON value into a string that can be indexed.
@@ -287,10 +439,10 @@ fn compute_language_frequency_threshold(languages_frequency: &[(Language, usize)
 
 #[derive(Default)]
 struct Buffers {
-    // the key buffer is the concatenation of the internal document id with the field id.
-    // The buffer has to be completelly cleared between documents,
-    // and the field id part must be cleared between each field.
-    key_buffer: Vec<u8>,
     // the field buffer for each fields desserialization, and must be cleared between each field.
     field_buffer: String,
+    // buffer used to store the value data containing an obkv.
+    obkv_buffer: Vec<u8>,
+    // buffer used to store the value data containing an obkv of tokens with their positions.
+    obkv_positions_buffer: Vec<u8>,
 }

milli/src/update/index_documents/extract/extract_facet_number_docids.rs

@@ -4,11 +4,12 @@ use std::io::{self, BufReader};
 use heed::{BytesDecode, BytesEncode};
 
 use super::helpers::{
-    create_sorter, merge_cbo_roaring_bitmaps, sorter_into_reader, GrenadParameters,
+    create_sorter, merge_deladd_cbo_roaring_bitmaps, sorter_into_reader, GrenadParameters,
 };
 use crate::heed_codec::facet::{
     FacetGroupKey, FacetGroupKeyCodec, FieldDocIdFacetF64Codec, OrderedF64Codec,
 };
+use crate::update::del_add::{KvReaderDelAdd, KvWriterDelAdd};
 use crate::Result;
 
 /// Extracts the facet number and the documents ids where this facet number appear.
@@ -17,7 +18,7 @@ use crate::Result;
 /// documents ids from the given chunk of docid facet number positions.
 #[logging_timer::time]
 pub fn extract_facet_number_docids<R: io::Read + io::Seek>(
-    docid_fid_facet_number: grenad::Reader<R>,
+    fid_docid_facet_number: grenad::Reader<R>,
     indexer: GrenadParameters,
 ) -> Result<grenad::Reader<BufReader<File>>> {
     puffin::profile_function!();
@@ -26,21 +27,30 @@ pub fn extract_facet_number_docids<R: io::Read + io::Seek>(
 
     let mut facet_number_docids_sorter = create_sorter(
         grenad::SortAlgorithm::Unstable,
-        merge_cbo_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
         indexer.max_nb_chunks,
         max_memory,
     );
 
-    let mut cursor = docid_fid_facet_number.into_cursor()?;
+    let mut buffer = Vec::new();
-    while let Some((key_bytes, _)) = cursor.move_on_next()? {
+    let mut cursor = fid_docid_facet_number.into_cursor()?;
+    while let Some((key_bytes, deladd_obkv_bytes)) = cursor.move_on_next()? {
         let (field_id, document_id, number) =
             FieldDocIdFacetF64Codec::bytes_decode(key_bytes).unwrap();
 
         let key = FacetGroupKey { field_id, level: 0, left_bound: number };
         let key_bytes = FacetGroupKeyCodec::<OrderedF64Codec>::bytes_encode(&key).unwrap();
-        facet_number_docids_sorter.insert(key_bytes, document_id.to_ne_bytes())?;
+
+        buffer.clear();
+        let mut obkv = KvWriterDelAdd::new(&mut buffer);
+        for (deladd_key, _) in KvReaderDelAdd::new(deladd_obkv_bytes).iter() {
+            obkv.insert(deladd_key, document_id.to_ne_bytes())?;
+        }
+        obkv.finish()?;
+
+        facet_number_docids_sorter.insert(key_bytes, &buffer)?;
     }
 
     sorter_into_reader(facet_number_docids_sorter, indexer)

milli/src/update/index_documents/extract/extract_facet_string_docids.rs

@@ -1,13 +1,15 @@
 use std::fs::File;
-use std::io::{self, BufReader};
+use std::io::BufReader;
+use std::{io, str};
 
 use heed::BytesEncode;
 
 use super::helpers::{create_sorter, sorter_into_reader, try_split_array_at, GrenadParameters};
 use crate::heed_codec::facet::{FacetGroupKey, FacetGroupKeyCodec};
 use crate::heed_codec::StrRefCodec;
-use crate::update::index_documents::merge_cbo_roaring_bitmaps;
+use crate::update::del_add::{KvReaderDelAdd, KvWriterDelAdd};
-use crate::{FieldId, Result, MAX_FACET_VALUE_LENGTH};
+use crate::update::index_documents::helpers::merge_deladd_cbo_roaring_bitmaps;
+use crate::{FieldId, Result};
 
 /// Extracts the facet string and the documents ids where this facet string appear.
 ///
@@ -24,15 +26,16 @@ pub fn extract_facet_string_docids<R: io::Read + io::Seek>(
 
     let mut facet_string_docids_sorter = create_sorter(
         grenad::SortAlgorithm::Stable,
-        merge_cbo_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
         indexer.max_nb_chunks,
         max_memory,
     );
 
+    let mut buffer = Vec::new();
     let mut cursor = docid_fid_facet_string.into_cursor()?;
-    while let Some((key, _original_value_bytes)) = cursor.move_on_next()? {
+    while let Some((key, deladd_original_value_bytes)) = cursor.move_on_next()? {
         let (field_id_bytes, bytes) = try_split_array_at(key).unwrap();
         let field_id = FieldId::from_be_bytes(field_id_bytes);
 
@@ -40,21 +43,17 @@ pub fn extract_facet_string_docids<R: io::Read + io::Seek>(
             try_split_array_at::<_, 4>(bytes).unwrap();
         let document_id = u32::from_be_bytes(document_id_bytes);
 
-        let mut normalised_value = std::str::from_utf8(normalized_value_bytes)?;
+        let normalized_value = str::from_utf8(normalized_value_bytes)?;
-
+        let key = FacetGroupKey { field_id, level: 0, left_bound: normalized_value };
-        let normalised_truncated_value: String;
-        if normalised_value.len() > MAX_FACET_VALUE_LENGTH {
-            normalised_truncated_value = normalised_value
-                .char_indices()
-                .take_while(|(idx, _)| *idx < MAX_FACET_VALUE_LENGTH)
-                .map(|(_, c)| c)
-                .collect();
-            normalised_value = normalised_truncated_value.as_str();
-        }
-        let key = FacetGroupKey { field_id, level: 0, left_bound: normalised_value };
         let key_bytes = FacetGroupKeyCodec::<StrRefCodec>::bytes_encode(&key).unwrap();
-        // document id is encoded in native-endian because of the CBO roaring bitmap codec
+
-        facet_string_docids_sorter.insert(&key_bytes, document_id.to_ne_bytes())?;
+        buffer.clear();
+        let mut obkv = KvWriterDelAdd::new(&mut buffer);
+        for (deladd_key, _) in KvReaderDelAdd::new(deladd_original_value_bytes).iter() {
+            obkv.insert(deladd_key, document_id.to_ne_bytes())?;
+        }
+        obkv.finish()?;
+        facet_string_docids_sorter.insert(&key_bytes, &buffer)?;
     }
 
     sorter_into_reader(facet_string_docids_sorter, indexer)

milli/src/update/index_documents/extract/extract_fid_docid_facet_values.rs

@@ -1,24 +1,36 @@
+use std::borrow::Cow;
 use std::collections::{BTreeMap, HashSet};
 use std::convert::TryInto;
 use std::fs::File;
 use std::io::{self, BufReader};
 use std::mem::size_of;
+use std::result::Result as StdResult;
 
+use grenad::Sorter;
 use heed::zerocopy::AsBytes;
 use heed::BytesEncode;
+use itertools::EitherOrBoth;
+use ordered_float::OrderedFloat;
 use roaring::RoaringBitmap;
 use serde_json::{from_slice, Value};
+use FilterableValues::{Empty, Null, Values};
 
 use super::helpers::{create_sorter, keep_first, sorter_into_reader, GrenadParameters};
 use crate::error::InternalError;
 use crate::facet::value_encoding::f64_into_bytes;
+use crate::update::del_add::{DelAdd, KvWriterDelAdd};
 use crate::update::index_documents::{create_writer, writer_into_reader};
-use crate::{CboRoaringBitmapCodec, DocumentId, FieldId, Result, BEU32, MAX_FACET_VALUE_LENGTH};
+use crate::{
+    CboRoaringBitmapCodec, DocumentId, Error, FieldId, Result, BEU32, MAX_FACET_VALUE_LENGTH,
+};
+
+/// The length of the elements that are always in the buffer when inserting new values.
+const TRUNCATE_SIZE: usize = size_of::<FieldId>() + size_of::<DocumentId>();
 
 /// The extracted facet values stored in grenad files by type.
 pub struct ExtractedFacetValues {
-    pub docid_fid_facet_numbers_chunk: grenad::Reader<BufReader<File>>,
+    pub fid_docid_facet_numbers_chunk: grenad::Reader<BufReader<File>>,
-    pub docid_fid_facet_strings_chunk: grenad::Reader<BufReader<File>>,
+    pub fid_docid_facet_strings_chunk: grenad::Reader<BufReader<File>>,
     pub fid_facet_is_null_docids_chunk: grenad::Reader<BufReader<File>>,
     pub fid_facet_is_empty_docids_chunk: grenad::Reader<BufReader<File>>,
     pub fid_facet_exists_docids_chunk: grenad::Reader<BufReader<File>>,
@@ -58,71 +70,150 @@ pub fn extract_fid_docid_facet_values<R: io::Read + io::Seek>(
         max_memory.map(|m| m / 2),
     );
 
-    let mut facet_exists_docids = BTreeMap::<FieldId, RoaringBitmap>::new();
+    // The tuples represents the Del and Add side for a bitmap
-    let mut facet_is_null_docids = BTreeMap::<FieldId, RoaringBitmap>::new();
+    let mut facet_exists_docids = BTreeMap::<FieldId, (RoaringBitmap, RoaringBitmap)>::new();
-    let mut facet_is_empty_docids = BTreeMap::<FieldId, RoaringBitmap>::new();
+    let mut facet_is_null_docids = BTreeMap::<FieldId, (RoaringBitmap, RoaringBitmap)>::new();
+    let mut facet_is_empty_docids = BTreeMap::<FieldId, (RoaringBitmap, RoaringBitmap)>::new();
+
+    // We create two buffers for mutable ref issues with closures.
+    let mut numbers_key_buffer = Vec::new();
+    let mut strings_key_buffer = Vec::new();
 
-    let mut key_buffer = Vec::new();
     let mut cursor = obkv_documents.into_cursor()?;
     while let Some((docid_bytes, value)) = cursor.move_on_next()? {
         let obkv = obkv::KvReader::new(value);
 
         for (field_id, field_bytes) in obkv.iter() {
             if faceted_fields.contains(&field_id) {
-                key_buffer.clear();
+                numbers_key_buffer.clear();
+                strings_key_buffer.clear();
 
                 // Set key to the field_id
                 // Note: this encoding is consistent with FieldIdCodec
-                key_buffer.extend_from_slice(&field_id.to_be_bytes());
+                numbers_key_buffer.extend_from_slice(&field_id.to_be_bytes());
+                strings_key_buffer.extend_from_slice(&field_id.to_be_bytes());
 
-                // Here, we know already that the document must be added to the “field id exists” database
                 let document: [u8; 4] = docid_bytes[..4].try_into().ok().unwrap();
                 let document = BEU32::from(document).get();
 
-                facet_exists_docids.entry(field_id).or_default().insert(document);
-
                 // For the other extraction tasks, prefix the key with the field_id and the document_id
-                key_buffer.extend_from_slice(docid_bytes);
+                numbers_key_buffer.extend_from_slice(docid_bytes);
+                strings_key_buffer.extend_from_slice(docid_bytes);
 
-                let value = from_slice(field_bytes).map_err(InternalError::SerdeJson)?;
+                let del_add_obkv = obkv::KvReader::new(field_bytes);
+                let del_value = match del_add_obkv.get(DelAdd::Deletion) {
+                    Some(bytes) => Some(from_slice(bytes).map_err(InternalError::SerdeJson)?),
+                    None => None,
+                };
+                let add_value = match del_add_obkv.get(DelAdd::Addition) {
+                    Some(bytes) => Some(from_slice(bytes).map_err(InternalError::SerdeJson)?),
+                    None => None,
+                };
 
-                match extract_facet_values(
+                // We insert the document id on the Del and the Add side if the field exists.
-                    &value,
+                let (ref mut del_exists, ref mut add_exists) =
-                    geo_fields_ids.map_or(false, |(lat, lng)| field_id == lat || field_id == lng),
+                    facet_exists_docids.entry(field_id).or_default();
-                ) {
+                let (ref mut del_is_null, ref mut add_is_null) =
-                    FilterableValues::Null => {
+                    facet_is_null_docids.entry(field_id).or_default();
-                        facet_is_null_docids.entry(field_id).or_default().insert(document);
+                let (ref mut del_is_empty, ref mut add_is_empty) =
-                    }
+                    facet_is_empty_docids.entry(field_id).or_default();
-                    FilterableValues::Empty => {
-                        facet_is_empty_docids.entry(field_id).or_default().insert(document);
-                    }
-                    FilterableValues::Values { numbers, strings } => {
-                        // insert facet numbers in sorter
-                        for number in numbers {
-                            key_buffer.truncate(size_of::<FieldId>() + size_of::<DocumentId>());
-                            if let Some(value_bytes) = f64_into_bytes(number) {
-                                key_buffer.extend_from_slice(&value_bytes);
-                                key_buffer.extend_from_slice(&number.to_be_bytes());
 
-                                fid_docid_facet_numbers_sorter
+                if del_value.is_some() {
-                                    .insert(&key_buffer, ().as_bytes())?;
+                    del_exists.insert(document);
-                            }
+                }
+                if add_value.is_some() {
+                    add_exists.insert(document);
+                }
+
+                let geo_support =
+                    geo_fields_ids.map_or(false, |(lat, lng)| field_id == lat || field_id == lng);
+                let del_filterable_values =
+                    del_value.map(|value| extract_facet_values(&value, geo_support));
+                let add_filterable_values =
+                    add_value.map(|value| extract_facet_values(&value, geo_support));
+
+                // Those closures are just here to simplify things a bit.
+                let mut insert_numbers_diff = |del_numbers, add_numbers| {
+                    insert_numbers_diff(
+                        &mut fid_docid_facet_numbers_sorter,
+                        &mut numbers_key_buffer,
+                        del_numbers,
+                        add_numbers,
+                    )
+                };
+                let mut insert_strings_diff = |del_strings, add_strings| {
+                    insert_strings_diff(
+                        &mut fid_docid_facet_strings_sorter,
+                        &mut strings_key_buffer,
+                        del_strings,
+                        add_strings,
+                    )
+                };
+
+                match (del_filterable_values, add_filterable_values) {
+                    (None, None) => (),
+                    (Some(del_filterable_values), None) => match del_filterable_values {
+                        Null => {
+                            del_is_null.insert(document);
                         }
-
+                        Empty => {
-                        // insert normalized and original facet string in sorter
+                            del_is_empty.insert(document);
-                        for (normalized, original) in
+                        }
-                            strings.into_iter().filter(|(n, _)| !n.is_empty())
+                        Values { numbers, strings } => {
-                        {
+                            insert_numbers_diff(numbers, vec![])?;
-                            let normalized_truncated_value: String = normalized
+                            insert_strings_diff(strings, vec![])?;
-                                .char_indices()
+                        }
-                                .take_while(|(idx, _)| idx + 4 < MAX_FACET_VALUE_LENGTH)
+                    },
-                                .map(|(_, c)| c)
+                    (None, Some(add_filterable_values)) => match add_filterable_values {
-                                .collect();
+                        Null => {
-
+                            add_is_null.insert(document);
-                            key_buffer.truncate(size_of::<FieldId>() + size_of::<DocumentId>());
+                        }
-                            key_buffer.extend_from_slice(normalized_truncated_value.as_bytes());
+                        Empty => {
-                            fid_docid_facet_strings_sorter
+                            add_is_empty.insert(document);
-                                .insert(&key_buffer, original.as_bytes())?;
+                        }
+                        Values { numbers, strings } => {
+                            insert_numbers_diff(vec![], numbers)?;
+                            insert_strings_diff(vec![], strings)?;
+                        }
+                    },
+                    (Some(del_filterable_values), Some(add_filterable_values)) => {
+                        match (del_filterable_values, add_filterable_values) {
+                            (Null, Null) | (Empty, Empty) => (),
+                            (Null, Empty) => {
+                                del_is_null.insert(document);
+                                add_is_empty.insert(document);
+                            }
+                            (Empty, Null) => {
+                                del_is_empty.insert(document);
+                                add_is_null.insert(document);
+                            }
+                            (Null, Values { numbers, strings }) => {
+                                insert_numbers_diff(vec![], numbers)?;
+                                insert_strings_diff(vec![], strings)?;
+                                del_is_null.insert(document);
+                            }
+                            (Empty, Values { numbers, strings }) => {
+                                insert_numbers_diff(vec![], numbers)?;
+                                insert_strings_diff(vec![], strings)?;
+                                del_is_empty.insert(document);
+                            }
+                            (Values { numbers, strings }, Null) => {
+                                add_is_null.insert(document);
+                                insert_numbers_diff(numbers, vec![])?;
+                                insert_strings_diff(strings, vec![])?;
+                            }
+                            (Values { numbers, strings }, Empty) => {
+                                add_is_empty.insert(document);
+                                insert_numbers_diff(numbers, vec![])?;
+                                insert_strings_diff(strings, vec![])?;
+                            }
+                            (
+                                Values { numbers: del_numbers, strings: del_strings },
+                                Values { numbers: add_numbers, strings: add_strings },
+                            ) => {
+                                insert_numbers_diff(del_numbers, add_numbers)?;
+                                insert_strings_diff(del_strings, add_strings)?;
+                            }
                         }
                     }
                 }
@@ -130,14 +221,15 @@ pub fn extract_fid_docid_facet_values<R: io::Read + io::Seek>(
         }
     }
 
+    let mut buffer = Vec::new();
     let mut facet_exists_docids_writer = create_writer(
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
         tempfile::tempfile()?,
     );
-    for (fid, bitmap) in facet_exists_docids.into_iter() {
+    for (fid, (del_bitmap, add_bitmap)) in facet_exists_docids.into_iter() {
-        let bitmap_bytes = CboRoaringBitmapCodec::bytes_encode(&bitmap).unwrap();
+        deladd_obkv_cbo_roaring_bitmaps(&mut buffer, &del_bitmap, &add_bitmap)?;
-        facet_exists_docids_writer.insert(fid.to_be_bytes(), &bitmap_bytes)?;
+        facet_exists_docids_writer.insert(fid.to_be_bytes(), &buffer)?;
     }
     let facet_exists_docids_reader = writer_into_reader(facet_exists_docids_writer)?;
 
@@ -146,9 +238,9 @@ pub fn extract_fid_docid_facet_values<R: io::Read + io::Seek>(
         indexer.chunk_compression_level,
         tempfile::tempfile()?,
     );
-    for (fid, bitmap) in facet_is_null_docids.into_iter() {
+    for (fid, (del_bitmap, add_bitmap)) in facet_is_null_docids.into_iter() {
-        let bitmap_bytes = CboRoaringBitmapCodec::bytes_encode(&bitmap).unwrap();
+        deladd_obkv_cbo_roaring_bitmaps(&mut buffer, &del_bitmap, &add_bitmap)?;
-        facet_is_null_docids_writer.insert(fid.to_be_bytes(), &bitmap_bytes)?;
+        facet_is_null_docids_writer.insert(fid.to_be_bytes(), &buffer)?;
     }
     let facet_is_null_docids_reader = writer_into_reader(facet_is_null_docids_writer)?;
 
@@ -157,21 +249,156 @@ pub fn extract_fid_docid_facet_values<R: io::Read + io::Seek>(
         indexer.chunk_compression_level,
         tempfile::tempfile()?,
     );
-    for (fid, bitmap) in facet_is_empty_docids.into_iter() {
+    for (fid, (del_bitmap, add_bitmap)) in facet_is_empty_docids.into_iter() {
-        let bitmap_bytes = CboRoaringBitmapCodec::bytes_encode(&bitmap).unwrap();
+        deladd_obkv_cbo_roaring_bitmaps(&mut buffer, &del_bitmap, &add_bitmap)?;
-        facet_is_empty_docids_writer.insert(fid.to_be_bytes(), &bitmap_bytes)?;
+        facet_is_empty_docids_writer.insert(fid.to_be_bytes(), &buffer)?;
     }
     let facet_is_empty_docids_reader = writer_into_reader(facet_is_empty_docids_writer)?;
 
     Ok(ExtractedFacetValues {
-        docid_fid_facet_numbers_chunk: sorter_into_reader(fid_docid_facet_numbers_sorter, indexer)?,
+        fid_docid_facet_numbers_chunk: sorter_into_reader(fid_docid_facet_numbers_sorter, indexer)?,
-        docid_fid_facet_strings_chunk: sorter_into_reader(fid_docid_facet_strings_sorter, indexer)?,
+        fid_docid_facet_strings_chunk: sorter_into_reader(fid_docid_facet_strings_sorter, indexer)?,
         fid_facet_is_null_docids_chunk: facet_is_null_docids_reader,
         fid_facet_is_empty_docids_chunk: facet_is_empty_docids_reader,
         fid_facet_exists_docids_chunk: facet_exists_docids_reader,
     })
 }
 
+/// Generates a vector of bytes containing a DelAdd obkv with two bitmaps.
+fn deladd_obkv_cbo_roaring_bitmaps(
+    buffer: &mut Vec<u8>,
+    del_bitmap: &RoaringBitmap,
+    add_bitmap: &RoaringBitmap,
+) -> io::Result<()> {
+    buffer.clear();
+    let mut obkv = KvWriterDelAdd::new(buffer);
+    let del_bitmap_bytes = CboRoaringBitmapCodec::bytes_encode(del_bitmap).unwrap();
+    let add_bitmap_bytes = CboRoaringBitmapCodec::bytes_encode(add_bitmap).unwrap();
+    obkv.insert(DelAdd::Deletion, del_bitmap_bytes)?;
+    obkv.insert(DelAdd::Addition, add_bitmap_bytes)?;
+    obkv.finish()
+}
+
+/// Truncates a string to the biggest valid LMDB key size.
+fn truncate_string(s: String) -> String {
+    s.char_indices()
+        .take_while(|(idx, _)| idx + 4 < MAX_FACET_VALUE_LENGTH)
+        .map(|(_, c)| c)
+        .collect()
+}
+
+/// Computes the diff between both Del and Add numbers and
+/// only inserts the parts that differ in the sorter.
+fn insert_numbers_diff<MF>(
+    fid_docid_facet_numbers_sorter: &mut Sorter<MF>,
+    key_buffer: &mut Vec<u8>,
+    mut del_numbers: Vec<f64>,
+    mut add_numbers: Vec<f64>,
+) -> Result<()>
+where
+    MF: for<'a> Fn(&[u8], &[Cow<'a, [u8]>]) -> StdResult<Cow<'a, [u8]>, Error>,
+{
+    // We sort and dedup the float numbers
+    del_numbers.sort_unstable_by_key(|f| OrderedFloat(*f));
+    add_numbers.sort_unstable_by_key(|f| OrderedFloat(*f));
+    del_numbers.dedup_by_key(|f| OrderedFloat(*f));
+    add_numbers.dedup_by_key(|f| OrderedFloat(*f));
+
+    let merged_numbers_iter = itertools::merge_join_by(
+        del_numbers.into_iter().map(OrderedFloat),
+        add_numbers.into_iter().map(OrderedFloat),
+        |del, add| del.cmp(add),
+    );
+
+    // insert facet numbers in sorter
+    for eob in merged_numbers_iter {
+        key_buffer.truncate(TRUNCATE_SIZE);
+        match eob {
+            EitherOrBoth::Both(_, _) => (), // no need to touch anything
+            EitherOrBoth::Left(OrderedFloat(number)) => {
+                if let Some(value_bytes) = f64_into_bytes(number) {
+                    key_buffer.extend_from_slice(&value_bytes);
+                    key_buffer.extend_from_slice(&number.to_be_bytes());
+
+                    // We insert only the Del part of the Obkv to inform
+                    // that we only want to remove all those numbers.
+                    let mut obkv = KvWriterDelAdd::memory();
+                    obkv.insert(DelAdd::Deletion, ().as_bytes())?;
+                    let bytes = obkv.into_inner()?;
+                    fid_docid_facet_numbers_sorter.insert(&key_buffer, bytes)?;
+                }
+            }
+            EitherOrBoth::Right(OrderedFloat(number)) => {
+                if let Some(value_bytes) = f64_into_bytes(number) {
+                    key_buffer.extend_from_slice(&value_bytes);
+                    key_buffer.extend_from_slice(&number.to_be_bytes());
+
+                    // We insert only the Add part of the Obkv to inform
+                    // that we only want to remove all those numbers.
+                    let mut obkv = KvWriterDelAdd::memory();
+                    obkv.insert(DelAdd::Addition, ().as_bytes())?;
+                    let bytes = obkv.into_inner()?;
+                    fid_docid_facet_numbers_sorter.insert(&key_buffer, bytes)?;
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
+
+/// Computes the diff between both Del and Add strings and
+/// only inserts the parts that differ in the sorter.
+fn insert_strings_diff<MF>(
+    fid_docid_facet_strings_sorter: &mut Sorter<MF>,
+    key_buffer: &mut Vec<u8>,
+    mut del_strings: Vec<(String, String)>,
+    mut add_strings: Vec<(String, String)>,
+) -> Result<()>
+where
+    MF: for<'a> Fn(&[u8], &[Cow<'a, [u8]>]) -> StdResult<Cow<'a, [u8]>, Error>,
+{
+    // We sort and dedup the normalized and original strings
+    del_strings.sort_unstable();
+    add_strings.sort_unstable();
+    del_strings.dedup();
+    add_strings.dedup();
+
+    let merged_strings_iter = itertools::merge_join_by(
+        del_strings.into_iter().filter(|(n, _)| !n.is_empty()),
+        add_strings.into_iter().filter(|(n, _)| !n.is_empty()),
+        |del, add| del.cmp(add),
+    );
+
+    // insert normalized and original facet string in sorter
+    for eob in merged_strings_iter {
+        key_buffer.truncate(TRUNCATE_SIZE);
+        match eob {
+            EitherOrBoth::Both(_, _) => (), // no need to touch anything
+            EitherOrBoth::Left((normalized, original)) => {
+                let truncated = truncate_string(normalized);
+                key_buffer.extend_from_slice(truncated.as_bytes());
+
+                let mut obkv = KvWriterDelAdd::memory();
+                obkv.insert(DelAdd::Deletion, original)?;
+                let bytes = obkv.into_inner()?;
+                fid_docid_facet_strings_sorter.insert(&key_buffer, bytes)?;
+            }
+            EitherOrBoth::Right((normalized, original)) => {
+                let truncated = truncate_string(normalized);
+                key_buffer.extend_from_slice(truncated.as_bytes());
+
+                let mut obkv = KvWriterDelAdd::memory();
+                obkv.insert(DelAdd::Addition, original)?;
+                let bytes = obkv.into_inner()?;
+                fid_docid_facet_strings_sorter.insert(&key_buffer, bytes)?;
+            }
+        }
+    }
+
+    Ok(())
+}
+
 /// Represent what a document field contains.
 enum FilterableValues {
     /// Corresponds to the JSON `null` value.
@@ -182,6 +409,7 @@ enum FilterableValues {
     Values { numbers: Vec<f64>, strings: Vec<(String, String)> },
 }
 
+/// Extracts the facet values of a JSON field.
 fn extract_facet_values(value: &Value, geo_field: bool) -> FilterableValues {
     fn inner_extract_facet_values(
         value: &Value,

milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs

@@ -1,16 +1,18 @@
-use std::collections::HashMap;
 use std::fs::File;
 use std::io::{self, BufReader};
 
-use grenad::Sorter;
+use obkv::KvReaderU16;
 
 use super::helpers::{
-    create_sorter, merge_cbo_roaring_bitmaps, read_u32_ne_bytes, sorter_into_reader,
+    create_sorter, merge_deladd_cbo_roaring_bitmaps, sorter_into_reader, try_split_array_at,
-    try_split_array_at, GrenadParameters, MergeFn,
+    GrenadParameters,
 };
 use crate::error::SerializationError;
 use crate::index::db_name::DOCID_WORD_POSITIONS;
-use crate::{relative_from_absolute_position, DocumentId, FieldId, Result};
+use crate::update::del_add::{DelAdd, KvReaderDelAdd, KvWriterDelAdd};
+use crate::Result;
+
+const MAX_COUNTED_WORDS: usize = 30;
 
 /// Extracts the field id word count and the documents ids where
 /// this field id with this amount of words appear.
@@ -28,70 +30,62 @@ pub fn extract_fid_word_count_docids<R: io::Read + io::Seek>(
 
     let mut fid_word_count_docids_sorter = create_sorter(
         grenad::SortAlgorithm::Unstable,
-        merge_cbo_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
         indexer.max_nb_chunks,
         max_memory,
     );
 
-    // This map is assumed to not consume a lot of memory.
+    let mut key_buffer = Vec::new();
-    let mut document_fid_wordcount = HashMap::new();
+    let mut value_buffer = Vec::new();
-    let mut current_document_id = None;
-
     let mut cursor = docid_word_positions.into_cursor()?;
     while let Some((key, value)) = cursor.move_on_next()? {
-        let (document_id_bytes, _word_bytes) = try_split_array_at(key)
+        let (document_id_bytes, fid_bytes) = try_split_array_at(key)
             .ok_or(SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
         let document_id = u32::from_be_bytes(document_id_bytes);
 
-        let curr_document_id = *current_document_id.get_or_insert(document_id);
+        let del_add_reader = KvReaderDelAdd::new(value);
-        if curr_document_id != document_id {
+        let deletion = del_add_reader
-            drain_document_fid_wordcount_into_sorter(
+            // get deleted words
-                &mut fid_word_count_docids_sorter,
+            .get(DelAdd::Deletion)
-                &mut document_fid_wordcount,
+            // count deleted words
-                curr_document_id,
+            .map(|deletion| KvReaderU16::new(deletion).iter().take(MAX_COUNTED_WORDS + 1).count())
-            )?;
+            // keep the count if under or equal to MAX_COUNTED_WORDS
-            current_document_id = Some(document_id);
+            .filter(|&word_count| word_count <= MAX_COUNTED_WORDS);
+        let addition = del_add_reader
+            // get added words
+            .get(DelAdd::Addition)
+            // count added words
+            .map(|addition| KvReaderU16::new(addition).iter().take(MAX_COUNTED_WORDS + 1).count())
+            // keep the count if under or equal to MAX_COUNTED_WORDS
+            .filter(|&word_count| word_count <= MAX_COUNTED_WORDS);
+
+        if deletion != addition {
+            // Insert deleted word count in sorter if exist.
+            if let Some(word_count) = deletion {
+                value_buffer.clear();
+                let mut value_writer = KvWriterDelAdd::new(&mut value_buffer);
+                value_writer.insert(DelAdd::Deletion, document_id.to_ne_bytes()).unwrap();
+                key_buffer.clear();
+                key_buffer.extend_from_slice(fid_bytes);
+                key_buffer.push(word_count as u8);
+                fid_word_count_docids_sorter
+                    .insert(&key_buffer, value_writer.into_inner().unwrap())?;
+            }
+            // Insert added word count in sorter if exist.
+            if let Some(word_count) = addition {
+                value_buffer.clear();
+                let mut value_writer = KvWriterDelAdd::new(&mut value_buffer);
+                value_writer.insert(DelAdd::Addition, document_id.to_ne_bytes()).unwrap();
+                key_buffer.clear();
+                key_buffer.extend_from_slice(fid_bytes);
+                key_buffer.push(word_count as u8);
+                fid_word_count_docids_sorter
+                    .insert(&key_buffer, value_writer.into_inner().unwrap())?;
+            }
         }
-
-        for position in read_u32_ne_bytes(value) {
-            let (field_id, _) = relative_from_absolute_position(position);
-
-            let value = document_fid_wordcount.entry(field_id as FieldId).or_insert(0);
-            *value += 1;
-        }
-    }
-
-    if let Some(document_id) = current_document_id {
-        // We must make sure that don't lose the current document field id
-        // word count map if we break because we reached the end of the chunk.
-        drain_document_fid_wordcount_into_sorter(
-            &mut fid_word_count_docids_sorter,
-            &mut document_fid_wordcount,
-            document_id,
-        )?;
     }
 
     sorter_into_reader(fid_word_count_docids_sorter, indexer)
 }
-
-fn drain_document_fid_wordcount_into_sorter(
-    fid_word_count_docids_sorter: &mut Sorter<MergeFn>,
-    document_fid_wordcount: &mut HashMap<FieldId, u32>,
-    document_id: DocumentId,
-) -> Result<()> {
-    let mut key_buffer = Vec::new();
-
-    for (fid, count) in document_fid_wordcount.drain() {
-        if count <= 30 {
-            key_buffer.clear();
-            key_buffer.extend_from_slice(&fid.to_be_bytes());
-            key_buffer.push(count as u8);
-
-            fid_word_count_docids_sorter.insert(&key_buffer, document_id.to_ne_bytes())?;
-        }
-    }
-
-    Ok(())
-}

milli/src/update/index_documents/extract/extract_geo_points.rs

@@ -6,6 +6,7 @@ use serde_json::Value;
 
 use super::helpers::{create_writer, writer_into_reader, GrenadParameters};
 use crate::error::GeoError;
+use crate::update::del_add::{DelAdd, KvReaderDelAdd, KvWriterDelAdd};
 use crate::update::index_documents::extract_finite_float_from_value;
 use crate::{FieldId, InternalError, Result};
 
@@ -30,39 +31,71 @@ pub fn extract_geo_points<R: io::Read + io::Seek>(
     let mut cursor = obkv_documents.into_cursor()?;
     while let Some((docid_bytes, value)) = cursor.move_on_next()? {
         let obkv = obkv::KvReader::new(value);
-        // since we only needs the primary key when we throw an error we create this getter to
+        // since we only need the primary key when we throw an error
-        // lazily get it when needed
+        // we create this getter to lazily get it when needed
         let document_id = || -> Value {
             let document_id = obkv.get(primary_key_id).unwrap();
             serde_json::from_slice(document_id).unwrap()
         };
 
         // first we get the two fields
-        let lat = obkv.get(lat_fid);
+        match (obkv.get(lat_fid), obkv.get(lng_fid)) {
-        let lng = obkv.get(lng_fid);
+            (Some(lat), Some(lng)) => {
+                let deladd_lat_obkv = KvReaderDelAdd::new(lat);
+                let deladd_lng_obkv = KvReaderDelAdd::new(lng);
 
-        if let Some((lat, lng)) = lat.zip(lng) {
+                // then we extract the values
-            // then we extract the values
+                let del_lat_lng = deladd_lat_obkv
-            let lat = extract_finite_float_from_value(
+                    .get(DelAdd::Deletion)
-                serde_json::from_slice(lat).map_err(InternalError::SerdeJson)?,
+                    .zip(deladd_lng_obkv.get(DelAdd::Deletion))
-            )
+                    .map(|(lat, lng)| extract_lat_lng(lat, lng, document_id))
-            .map_err(|lat| GeoError::BadLatitude { document_id: document_id(), value: lat })?;
+                    .transpose()?;
+                let add_lat_lng = deladd_lat_obkv
+                    .get(DelAdd::Addition)
+                    .zip(deladd_lng_obkv.get(DelAdd::Addition))
+                    .map(|(lat, lng)| extract_lat_lng(lat, lng, document_id))
+                    .transpose()?;
 
-            let lng = extract_finite_float_from_value(
+                if del_lat_lng != add_lat_lng {
-                serde_json::from_slice(lng).map_err(InternalError::SerdeJson)?,
+                    let mut obkv = KvWriterDelAdd::memory();
-            )
+                    if let Some([lat, lng]) = del_lat_lng {
-            .map_err(|lng| GeoError::BadLongitude { document_id: document_id(), value: lng })?;
+                        #[allow(clippy::drop_non_drop)]
-
+                        let bytes: [u8; 16] = concat_arrays![lat.to_ne_bytes(), lng.to_ne_bytes()];
-            #[allow(clippy::drop_non_drop)]
+                        obkv.insert(DelAdd::Deletion, bytes)?;
-            let bytes: [u8; 16] = concat_arrays![lat.to_ne_bytes(), lng.to_ne_bytes()];
+                    }
-            writer.insert(docid_bytes, bytes)?;
+                    if let Some([lat, lng]) = add_lat_lng {
-        } else if lat.is_none() && lng.is_some() {
+                        #[allow(clippy::drop_non_drop)]
-            return Err(GeoError::MissingLatitude { document_id: document_id() })?;
+                        let bytes: [u8; 16] = concat_arrays![lat.to_ne_bytes(), lng.to_ne_bytes()];
-        } else if lat.is_some() && lng.is_none() {
+                        obkv.insert(DelAdd::Addition, bytes)?;
-            return Err(GeoError::MissingLongitude { document_id: document_id() })?;
+                    }
+                    let bytes = obkv.into_inner()?;
+                    writer.insert(docid_bytes, bytes)?;
+                }
+            }
+            (None, Some(_)) => {
+                return Err(GeoError::MissingLatitude { document_id: document_id() }.into())
+            }
+            (Some(_), None) => {
+                return Err(GeoError::MissingLongitude { document_id: document_id() }.into())
+            }
+            (None, None) => (),
         }
-        // else => the _geo object was `null`, there is nothing to do
     }
 
     writer_into_reader(writer)
 }
+
+/// Extract the finite floats lat and lng from two bytes slices.
+fn extract_lat_lng(lat: &[u8], lng: &[u8], document_id: impl Fn() -> Value) -> Result<[f64; 2]> {
+    let lat = extract_finite_float_from_value(
+        serde_json::from_slice(lat).map_err(InternalError::SerdeJson)?,
+    )
+    .map_err(|lat| GeoError::BadLatitude { document_id: document_id(), value: lat })?;
+
+    let lng = extract_finite_float_from_value(
+        serde_json::from_slice(lng).map_err(InternalError::SerdeJson)?,
+    )
+    .map_err(|lng| GeoError::BadLongitude { document_id: document_id(), value: lng })?;
+
+    Ok([lat, lng])
+}

milli/src/update/index_documents/extract/extract_vector_points.rs

@@ -1,13 +1,24 @@
+use std::cmp::Ordering;
 use std::convert::TryFrom;
 use std::fs::File;
-use std::io::{self, BufReader};
+use std::io::{self, BufReader, BufWriter};
+use std::mem::size_of;
+use std::str::from_utf8;
 
 use bytemuck::cast_slice;
+use grenad::Writer;
+use itertools::EitherOrBoth;
+use ordered_float::OrderedFloat;
 use serde_json::{from_slice, Value};
 
 use super::helpers::{create_writer, writer_into_reader, GrenadParameters};
 use crate::error::UserError;
-use crate::{FieldId, InternalError, Result, VectorOrArrayOfVectors};
+use crate::update::del_add::{DelAdd, KvReaderDelAdd, KvWriterDelAdd};
+use crate::update::index_documents::helpers::try_split_at;
+use crate::{DocumentId, FieldId, InternalError, Result, VectorOrArrayOfVectors};
+
+/// The length of the elements that are always in the buffer when inserting new values.
+const TRUNCATE_SIZE: usize = size_of::<DocumentId>();
 
 /// Extracts the embedding vector contained in each document under the `_vectors` field.
 ///
@@ -16,7 +27,6 @@ use crate::{FieldId, InternalError, Result, VectorOrArrayOfVectors};
 pub fn extract_vector_points<R: io::Read + io::Seek>(
     obkv_documents: grenad::Reader<R>,
     indexer: GrenadParameters,
-    primary_key_id: FieldId,
     vectors_fid: FieldId,
 ) -> Result<grenad::Reader<BufReader<File>>> {
     puffin::profile_function!();
@@ -27,43 +37,112 @@ pub fn extract_vector_points<R: io::Read + io::Seek>(
         tempfile::tempfile()?,
     );
 
+    let mut key_buffer = Vec::new();
     let mut cursor = obkv_documents.into_cursor()?;
-    while let Some((docid_bytes, value)) = cursor.move_on_next()? {
+    while let Some((key, value)) = cursor.move_on_next()? {
+        // this must always be serialized as (docid, external_docid);
+        let (docid_bytes, external_id_bytes) =
+            try_split_at(key, std::mem::size_of::<DocumentId>()).unwrap();
+        debug_assert!(from_utf8(external_id_bytes).is_ok());
+
         let obkv = obkv::KvReader::new(value);
+        key_buffer.clear();
+        key_buffer.extend_from_slice(docid_bytes);
 
         // since we only needs the primary key when we throw an error we create this getter to
         // lazily get it when needed
-        let document_id = || -> Value {
+        let document_id = || -> Value { from_utf8(external_id_bytes).unwrap().into() };
-            let document_id = obkv.get(primary_key_id).unwrap();
-            from_slice(document_id).unwrap()
-        };
 
         // first we retrieve the _vectors field
-        if let Some(vectors) = obkv.get(vectors_fid) {
+        if let Some(value) = obkv.get(vectors_fid) {
-            // extract the vectors
+            let vectors_obkv = KvReaderDelAdd::new(value);
-            let vectors = match from_slice(vectors) {
-                Ok(vectors) => VectorOrArrayOfVectors::into_array_of_vectors(vectors),
-                Err(_) => {
-                    return Err(UserError::InvalidVectorsType {
-                        document_id: document_id(),
-                        value: from_slice(vectors).map_err(InternalError::SerdeJson)?,
-                    }
-                    .into())
-                }
-            };
 
-            if let Some(vectors) = vectors {
+            // then we extract the values
-                for (i, vector) in vectors.into_iter().enumerate().take(u16::MAX as usize) {
+            let del_vectors = vectors_obkv
-                    let index = u16::try_from(i).unwrap();
+                .get(DelAdd::Deletion)
-                    let mut key = docid_bytes.to_vec();
+                .map(|vectors| extract_vectors(vectors, document_id))
-                    key.extend_from_slice(&index.to_be_bytes());
+                .transpose()?
-                    let bytes = cast_slice(&vector);
+                .flatten();
-                    writer.insert(key, bytes)?;
+            let add_vectors = vectors_obkv
-                }
+                .get(DelAdd::Addition)
-            }
+                .map(|vectors| extract_vectors(vectors, document_id))
+                .transpose()?
+                .flatten();
+
+            // and we finally push the unique vectors into the writer
+            push_vectors_diff(
+                &mut writer,
+                &mut key_buffer,
+                del_vectors.unwrap_or_default(),
+                add_vectors.unwrap_or_default(),
+            )?;
         }
-        // else => the `_vectors` object was `null`, there is nothing to do
     }
 
     writer_into_reader(writer)
 }
+
+/// Computes the diff between both Del and Add numbers and
+/// only inserts the parts that differ in the sorter.
+fn push_vectors_diff(
+    writer: &mut Writer<BufWriter<File>>,
+    key_buffer: &mut Vec<u8>,
+    mut del_vectors: Vec<Vec<f32>>,
+    mut add_vectors: Vec<Vec<f32>>,
+) -> Result<()> {
+    // We sort and dedup the vectors
+    del_vectors.sort_unstable_by(|a, b| compare_vectors(a, b));
+    add_vectors.sort_unstable_by(|a, b| compare_vectors(a, b));
+    del_vectors.dedup_by(|a, b| compare_vectors(a, b).is_eq());
+    add_vectors.dedup_by(|a, b| compare_vectors(a, b).is_eq());
+
+    let merged_vectors_iter =
+        itertools::merge_join_by(del_vectors, add_vectors, |del, add| compare_vectors(del, add));
+
+    // insert vectors into the writer
+    for (i, eob) in merged_vectors_iter.into_iter().enumerate().take(u16::MAX as usize) {
+        // Generate the key by extending the unique index to it.
+        key_buffer.truncate(TRUNCATE_SIZE);
+        let index = u16::try_from(i).unwrap();
+        key_buffer.extend_from_slice(&index.to_be_bytes());
+
+        match eob {
+            EitherOrBoth::Both(_, _) => (), // no need to touch anything
+            EitherOrBoth::Left(vector) => {
+                // We insert only the Del part of the Obkv to inform
+                // that we only want to remove all those vectors.
+                let mut obkv = KvWriterDelAdd::memory();
+                obkv.insert(DelAdd::Deletion, cast_slice(&vector))?;
+                let bytes = obkv.into_inner()?;
+                writer.insert(&key_buffer, bytes)?;
+            }
+            EitherOrBoth::Right(vector) => {
+                // We insert only the Add part of the Obkv to inform
+                // that we only want to remove all those vectors.
+                let mut obkv = KvWriterDelAdd::memory();
+                obkv.insert(DelAdd::Addition, cast_slice(&vector))?;
+                let bytes = obkv.into_inner()?;
+                writer.insert(&key_buffer, bytes)?;
+            }
+        }
+    }
+
+    Ok(())
+}
+
+/// Compares two vectors by using the OrderingFloat helper.
+fn compare_vectors(a: &[f32], b: &[f32]) -> Ordering {
+    a.iter().copied().map(OrderedFloat).cmp(b.iter().copied().map(OrderedFloat))
+}
+
+/// Extracts the vectors from a JSON value.
+fn extract_vectors(value: &[u8], document_id: impl Fn() -> Value) -> Result<Option<Vec<Vec<f32>>>> {
+    match from_slice(value) {
+        Ok(vectors) => Ok(VectorOrArrayOfVectors::into_array_of_vectors(vectors)),
+        Err(_) => Err(UserError::InvalidVectorsType {
+            document_id: document_id(),
+            value: from_slice(value).map_err(InternalError::SerdeJson)?,
+        }
+        .into()),
+    }
+}

milli/src/update/index_documents/extract/extract_word_docids.rs

@@ -1,18 +1,20 @@
-use std::collections::HashSet;
+use std::collections::{BTreeSet, HashSet};
 use std::fs::File;
 use std::io::{self, BufReader};
-use std::iter::FromIterator;
 
-use roaring::RoaringBitmap;
+use heed::BytesDecode;
+use obkv::KvReaderU16;
 
 use super::helpers::{
-    create_sorter, merge_roaring_bitmaps, serialize_roaring_bitmap, sorter_into_reader,
+    create_sorter, create_writer, merge_deladd_cbo_roaring_bitmaps, sorter_into_reader,
-    try_split_array_at, GrenadParameters,
+    try_split_array_at, writer_into_reader, GrenadParameters,
 };
 use crate::error::SerializationError;
+use crate::heed_codec::StrBEU16Codec;
 use crate::index::db_name::DOCID_WORD_POSITIONS;
-use crate::update::index_documents::helpers::read_u32_ne_bytes;
+use crate::update::del_add::{is_noop_del_add_obkv, DelAdd, KvReaderDelAdd, KvWriterDelAdd};
-use crate::{relative_from_absolute_position, FieldId, Result};
+use crate::update::MergeFn;
+use crate::{DocumentId, FieldId, Result};
 
 /// Extracts the word and the documents ids where this word appear.
 ///
@@ -26,65 +28,152 @@ pub fn extract_word_docids<R: io::Read + io::Seek>(
     docid_word_positions: grenad::Reader<R>,
     indexer: GrenadParameters,
     exact_attributes: &HashSet<FieldId>,
-) -> Result<(grenad::Reader<BufReader<File>>, grenad::Reader<BufReader<File>>)> {
+) -> Result<(
+    grenad::Reader<BufReader<File>>,
+    grenad::Reader<BufReader<File>>,
+    grenad::Reader<BufReader<File>>,
+)> {
     puffin::profile_function!();
 
     let max_memory = indexer.max_memory_by_thread();
 
-    let mut word_docids_sorter = create_sorter(
+    let mut word_fid_docids_sorter = create_sorter(
         grenad::SortAlgorithm::Unstable,
-        merge_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
         indexer.max_nb_chunks,
-        max_memory.map(|x| x / 2),
+        max_memory.map(|x| x / 3),
+    );
+    let mut key_buffer = Vec::new();
+    let mut del_words = BTreeSet::new();
+    let mut add_words = BTreeSet::new();
+    let mut cursor = docid_word_positions.into_cursor()?;
+    while let Some((key, value)) = cursor.move_on_next()? {
+        let (document_id_bytes, fid_bytes) = try_split_array_at(key)
+            .ok_or(SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
+        let (fid_bytes, _) = try_split_array_at(fid_bytes)
+            .ok_or(SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
+        let document_id = u32::from_be_bytes(document_id_bytes);
+        let fid = u16::from_be_bytes(fid_bytes);
+
+        let del_add_reader = KvReaderDelAdd::new(value);
+        // extract all unique words to remove.
+        if let Some(deletion) = del_add_reader.get(DelAdd::Deletion) {
+            for (_pos, word) in KvReaderU16::new(deletion).iter() {
+                del_words.insert(word.to_vec());
+            }
+        }
+
+        // extract all unique additional words.
+        if let Some(addition) = del_add_reader.get(DelAdd::Addition) {
+            for (_pos, word) in KvReaderU16::new(addition).iter() {
+                add_words.insert(word.to_vec());
+            }
+        }
+
+        words_into_sorter(
+            document_id,
+            fid,
+            &mut key_buffer,
+            &del_words,
+            &add_words,
+            &mut word_fid_docids_sorter,
+        )?;
+
+        del_words.clear();
+        add_words.clear();
+    }
+
+    let mut word_docids_sorter = create_sorter(
+        grenad::SortAlgorithm::Unstable,
+        merge_deladd_cbo_roaring_bitmaps,
+        indexer.chunk_compression_type,
+        indexer.chunk_compression_level,
+        indexer.max_nb_chunks,
+        max_memory.map(|x| x / 3),
     );
 
     let mut exact_word_docids_sorter = create_sorter(
         grenad::SortAlgorithm::Unstable,
-        merge_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
         indexer.max_nb_chunks,
-        max_memory.map(|x| x / 2),
+        max_memory.map(|x| x / 3),
     );
 
-    let mut value_buffer = Vec::new();
+    let mut word_fid_docids_writer = create_writer(
-    let mut cursor = docid_word_positions.into_cursor()?;
+        indexer.chunk_compression_type,
-    while let Some((key, positions)) = cursor.move_on_next()? {
+        indexer.chunk_compression_level,
-        let (document_id_bytes, word_bytes) = try_split_array_at(key)
+        tempfile::tempfile()?,
+    );
+
+    let mut iter = word_fid_docids_sorter.into_stream_merger_iter()?;
+    // TODO: replace sorters by writers by accumulating values into a buffer before inserting them.
+    while let Some((key, value)) = iter.next()? {
+        // only keep the value if their is a change to apply in the DB.
+        if !is_noop_del_add_obkv(KvReaderDelAdd::new(value)) {
+            word_fid_docids_writer.insert(key, value)?;
+        }
+
+        let (word, fid) = StrBEU16Codec::bytes_decode(key)
             .ok_or(SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
-        let document_id = u32::from_be_bytes(document_id_bytes);
 
-        let bitmap = RoaringBitmap::from_iter(Some(document_id));
+        // every words contained in an attribute set to exact must be pushed in the exact_words list.
-        serialize_roaring_bitmap(&bitmap, &mut value_buffer)?;
+        if exact_attributes.contains(&fid) {
-
+            exact_word_docids_sorter.insert(word.as_bytes(), value)?;
-        // If there are no exact attributes, we do not need to iterate over positions.
-        if exact_attributes.is_empty() {
-            word_docids_sorter.insert(word_bytes, &value_buffer)?;
         } else {
-            let mut added_to_exact = false;
+            word_docids_sorter.insert(word.as_bytes(), value)?;
-            let mut added_to_word_docids = false;
-            for position in read_u32_ne_bytes(positions) {
-                // as soon as we know that this word had been to both readers, we don't need to
-                // iterate over the positions.
-                if added_to_exact && added_to_word_docids {
-                    break;
-                }
-                let (fid, _) = relative_from_absolute_position(position);
-                if exact_attributes.contains(&fid) && !added_to_exact {
-                    exact_word_docids_sorter.insert(word_bytes, &value_buffer)?;
-                    added_to_exact = true;
-                } else if !added_to_word_docids {
-                    word_docids_sorter.insert(word_bytes, &value_buffer)?;
-                    added_to_word_docids = true;
-                }
-            }
         }
     }
 
     Ok((
         sorter_into_reader(word_docids_sorter, indexer)?,
         sorter_into_reader(exact_word_docids_sorter, indexer)?,
+        writer_into_reader(word_fid_docids_writer)?,
     ))
 }
+
+fn words_into_sorter(
+    document_id: DocumentId,
+    fid: FieldId,
+    key_buffer: &mut Vec<u8>,
+    del_words: &BTreeSet<Vec<u8>>,
+    add_words: &BTreeSet<Vec<u8>>,
+    word_fid_docids_sorter: &mut grenad::Sorter<MergeFn>,
+) -> Result<()> {
+    puffin::profile_function!();
+
+    use itertools::merge_join_by;
+    use itertools::EitherOrBoth::{Both, Left, Right};
+
+    let mut buffer = Vec::new();
+    for eob in merge_join_by(del_words.iter(), add_words.iter(), |d, a| d.cmp(a)) {
+        buffer.clear();
+        let mut value_writer = KvWriterDelAdd::new(&mut buffer);
+        let word_bytes = match eob {
+            Left(word_bytes) => {
+                value_writer.insert(DelAdd::Deletion, document_id.to_ne_bytes()).unwrap();
+                word_bytes
+            }
+            Right(word_bytes) => {
+                value_writer.insert(DelAdd::Addition, document_id.to_ne_bytes()).unwrap();
+                word_bytes
+            }
+            Both(word_bytes, _) => {
+                value_writer.insert(DelAdd::Deletion, document_id.to_ne_bytes()).unwrap();
+                value_writer.insert(DelAdd::Addition, document_id.to_ne_bytes()).unwrap();
+                word_bytes
+            }
+        };
+
+        key_buffer.clear();
+        key_buffer.extend_from_slice(word_bytes);
+        key_buffer.push(0);
+        key_buffer.extend_from_slice(&fid.to_be_bytes());
+        word_fid_docids_sorter.insert(&key_buffer, value_writer.into_inner().unwrap())?;
+    }
+
+    Ok(())
+}

milli/src/update/index_documents/extract/extract_word_fid_docids.rs

@@ -1,51 +0,0 @@
-use std::fs::File;
-use std::io::{self, BufReader};
-
-use super::helpers::{
-    create_sorter, merge_cbo_roaring_bitmaps, read_u32_ne_bytes, sorter_into_reader,
-    try_split_array_at, GrenadParameters,
-};
-use crate::error::SerializationError;
-use crate::index::db_name::DOCID_WORD_POSITIONS;
-use crate::{relative_from_absolute_position, DocumentId, Result};
-
-/// Extracts the word, field id, and the documents ids where this word appear at this field id.
-#[logging_timer::time]
-pub fn extract_word_fid_docids<R: io::Read + io::Seek>(
-    docid_word_positions: grenad::Reader<R>,
-    indexer: GrenadParameters,
-) -> Result<grenad::Reader<BufReader<File>>> {
-    puffin::profile_function!();
-
-    let max_memory = indexer.max_memory_by_thread();
-
-    let mut word_fid_docids_sorter = create_sorter(
-        grenad::SortAlgorithm::Unstable,
-        merge_cbo_roaring_bitmaps,
-        indexer.chunk_compression_type,
-        indexer.chunk_compression_level,
-        indexer.max_nb_chunks,
-        max_memory,
-    );
-
-    let mut key_buffer = Vec::new();
-    let mut cursor = docid_word_positions.into_cursor()?;
-    while let Some((key, value)) = cursor.move_on_next()? {
-        let (document_id_bytes, word_bytes) = try_split_array_at(key)
-            .ok_or(SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
-        let document_id = DocumentId::from_be_bytes(document_id_bytes);
-
-        for position in read_u32_ne_bytes(value) {
-            key_buffer.clear();
-            key_buffer.extend_from_slice(word_bytes);
-            key_buffer.push(0);
-            let (fid, _) = relative_from_absolute_position(position);
-            key_buffer.extend_from_slice(&fid.to_be_bytes());
-            word_fid_docids_sorter.insert(&key_buffer, document_id.to_ne_bytes())?;
-        }
-    }
-
-    let word_fid_docids_reader = sorter_into_reader(word_fid_docids_sorter, indexer)?;
-
-    Ok(word_fid_docids_reader)
-}

milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs

@@ -1,16 +1,18 @@
-use std::cmp::Ordering;
+use std::collections::{BTreeMap, VecDeque};
-use std::collections::{BinaryHeap, HashMap};
 use std::fs::File;
 use std::io::BufReader;
-use std::{cmp, io, mem, str, vec};
+use std::{cmp, io};
+
+use obkv::KvReaderU16;
 
 use super::helpers::{
-    create_sorter, merge_cbo_roaring_bitmaps, read_u32_ne_bytes, sorter_into_reader,
+    create_sorter, create_writer, merge_deladd_cbo_roaring_bitmaps, try_split_array_at,
-    try_split_array_at, GrenadParameters, MergeFn,
+    writer_into_reader, GrenadParameters, MergeFn,
 };
 use crate::error::SerializationError;
 use crate::index::db_name::DOCID_WORD_POSITIONS;
-use crate::proximity::{positions_proximity, MAX_DISTANCE};
+use crate::proximity::{index_proximity, MAX_DISTANCE};
+use crate::update::del_add::{DelAdd, KvReaderDelAdd, KvWriterDelAdd};
 use crate::{DocumentId, Result};
 
 /// Extracts the best proximity between pairs of words and the documents ids where this pair appear.
@@ -26,58 +28,137 @@ pub fn extract_word_pair_proximity_docids<R: io::Read + io::Seek>(
 
     let max_memory = indexer.max_memory_by_thread();
 
-    let mut word_pair_proximity_docids_sorter = create_sorter(
+    let mut word_pair_proximity_docids_sorters: Vec<_> = (1..MAX_DISTANCE)
-        grenad::SortAlgorithm::Unstable,
+        .map(|_| {
-        merge_cbo_roaring_bitmaps,
+            create_sorter(
-        indexer.chunk_compression_type,
+                grenad::SortAlgorithm::Unstable,
-        indexer.chunk_compression_level,
+                merge_deladd_cbo_roaring_bitmaps,
-        indexer.max_nb_chunks,
+                indexer.chunk_compression_type,
-        max_memory.map(|m| m / 2),
+                indexer.chunk_compression_level,
-    );
+                indexer.max_nb_chunks,
+                max_memory.map(|m| m / MAX_DISTANCE as usize),
+            )
+        })
+        .collect();
 
-    // This map is assumed to not consume a lot of memory.
+    let mut del_word_positions: VecDeque<(String, u16)> =
-    let mut document_word_positions_heap = BinaryHeap::new();
+        VecDeque::with_capacity(MAX_DISTANCE as usize);
+    let mut add_word_positions: VecDeque<(String, u16)> =
+        VecDeque::with_capacity(MAX_DISTANCE as usize);
+    let mut del_word_pair_proximity = BTreeMap::new();
+    let mut add_word_pair_proximity = BTreeMap::new();
     let mut current_document_id = None;
 
     let mut cursor = docid_word_positions.into_cursor()?;
     while let Some((key, value)) = cursor.move_on_next()? {
-        let (document_id_bytes, word_bytes) = try_split_array_at(key)
+        let (document_id_bytes, _fid_bytes) = try_split_array_at(key)
             .ok_or(SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
         let document_id = u32::from_be_bytes(document_id_bytes);
-        let word = str::from_utf8(word_bytes)?;
 
-        let curr_document_id = *current_document_id.get_or_insert(document_id);
+        // if we change document, we fill the sorter
-        if curr_document_id != document_id {
+        if current_document_id.map_or(false, |id| id != document_id) {
-            let document_word_positions_heap = mem::take(&mut document_word_positions_heap);
+            puffin::profile_scope!("Document into sorter");
+
             document_word_positions_into_sorter(
-                curr_document_id,
+                current_document_id.unwrap(),
-                document_word_positions_heap,
+                &del_word_pair_proximity,
-                &mut word_pair_proximity_docids_sorter,
+                &add_word_pair_proximity,
+                &mut word_pair_proximity_docids_sorters,
             )?;
-            current_document_id = Some(document_id);
+            del_word_pair_proximity.clear();
+            add_word_pair_proximity.clear();
         }
 
-        let word = word.to_string();
+        current_document_id = Some(document_id);
-        let mut positions: Vec<_> = read_u32_ne_bytes(value).collect();
+
-        positions.sort_unstable();
+        let (del, add): (Result<_>, Result<_>) = rayon::join(
-        let mut iter = positions.into_iter();
+            || {
-        if let Some(position) = iter.next() {
+                // deletions
-            document_word_positions_heap.push(PeekedWordPosition { word, position, iter });
+                if let Some(deletion) = KvReaderDelAdd::new(value).get(DelAdd::Deletion) {
-        }
+                    for (position, word) in KvReaderU16::new(deletion).iter() {
+                        // drain the proximity window until the head word is considered close to the word we are inserting.
+                        while del_word_positions.get(0).map_or(false, |(_w, p)| {
+                            index_proximity(*p as u32, position as u32) >= MAX_DISTANCE
+                        }) {
+                            word_positions_into_word_pair_proximity(
+                                &mut del_word_positions,
+                                &mut del_word_pair_proximity,
+                            )?;
+                        }
+
+                        // insert the new word.
+                        let word = std::str::from_utf8(word)?;
+                        del_word_positions.push_back((word.to_string(), position));
+                    }
+
+                    while !del_word_positions.is_empty() {
+                        word_positions_into_word_pair_proximity(
+                            &mut del_word_positions,
+                            &mut del_word_pair_proximity,
+                        )?;
+                    }
+                }
+
+                Ok(())
+            },
+            || {
+                // additions
+                if let Some(addition) = KvReaderDelAdd::new(value).get(DelAdd::Addition) {
+                    for (position, word) in KvReaderU16::new(addition).iter() {
+                        // drain the proximity window until the head word is considered close to the word we are inserting.
+                        while add_word_positions.get(0).map_or(false, |(_w, p)| {
+                            index_proximity(*p as u32, position as u32) >= MAX_DISTANCE
+                        }) {
+                            word_positions_into_word_pair_proximity(
+                                &mut add_word_positions,
+                                &mut add_word_pair_proximity,
+                            )?;
+                        }
+
+                        // insert the new word.
+                        let word = std::str::from_utf8(word)?;
+                        add_word_positions.push_back((word.to_string(), position));
+                    }
+
+                    while !add_word_positions.is_empty() {
+                        word_positions_into_word_pair_proximity(
+                            &mut add_word_positions,
+                            &mut add_word_pair_proximity,
+                        )?;
+                    }
+                }
+
+                Ok(())
+            },
+        );
+
+        del?;
+        add?;
     }
 
     if let Some(document_id) = current_document_id {
-        // We must make sure that don't lose the current document field id
+        puffin::profile_scope!("Final document into sorter");
-        // word count map if we break because we reached the end of the chunk.
-        let document_word_positions_heap = mem::take(&mut document_word_positions_heap);
         document_word_positions_into_sorter(
             document_id,
-            document_word_positions_heap,
+            &del_word_pair_proximity,
-            &mut word_pair_proximity_docids_sorter,
+            &add_word_pair_proximity,
+            &mut word_pair_proximity_docids_sorters,
         )?;
     }
+    {
+        puffin::profile_scope!("sorter_into_reader");
+        let mut writer = create_writer(
+            indexer.chunk_compression_type,
+            indexer.chunk_compression_level,
+            tempfile::tempfile()?,
+        );
 
-    sorter_into_reader(word_pair_proximity_docids_sorter, indexer)
+        for sorter in word_pair_proximity_docids_sorters {
+            sorter.write_into_stream_writer(&mut writer)?;
+        }
+
+        writer_into_reader(writer)
+    }
 }
 
 /// Fills the list of all pairs of words with the shortest proximity between 1 and 7 inclusive.
@@ -86,96 +167,66 @@ pub fn extract_word_pair_proximity_docids<R: io::Read + io::Seek>(
 /// close to each other.
 fn document_word_positions_into_sorter(
     document_id: DocumentId,
-    mut word_positions_heap: BinaryHeap<PeekedWordPosition<vec::IntoIter<u32>>>,
+    del_word_pair_proximity: &BTreeMap<(String, String), u8>,
-    word_pair_proximity_docids_sorter: &mut grenad::Sorter<MergeFn>,
+    add_word_pair_proximity: &BTreeMap<(String, String), u8>,
+    word_pair_proximity_docids_sorters: &mut [grenad::Sorter<MergeFn>],
 ) -> Result<()> {
-    let mut word_pair_proximity = HashMap::new();
+    use itertools::merge_join_by;
-    let mut ordered_peeked_word_positions = Vec::new();
+    use itertools::EitherOrBoth::{Both, Left, Right};
-    while !word_positions_heap.is_empty() {
-        while let Some(peeked_word_position) = word_positions_heap.pop() {
-            ordered_peeked_word_positions.push(peeked_word_position);
-            if ordered_peeked_word_positions.len() == 7 {
-                break;
-            }
-        }
-
-        if let Some((head, tail)) = ordered_peeked_word_positions.split_first() {
-            for PeekedWordPosition { word, position, .. } in tail {
-                let prox = positions_proximity(head.position, *position);
-                if prox > 0 && prox < MAX_DISTANCE {
-                    word_pair_proximity
-                        .entry((head.word.clone(), word.clone()))
-                        .and_modify(|p| {
-                            *p = cmp::min(*p, prox);
-                        })
-                        .or_insert(prox);
-                }
-            }
-
-            // Push the tail in the heap.
-            let tail_iter = ordered_peeked_word_positions.drain(1..);
-            word_positions_heap.extend(tail_iter);
-
-            // Advance the head and push it in the heap.
-            if let Some(mut head) = ordered_peeked_word_positions.pop() {
-                if let Some(next_position) = head.iter.next() {
-                    let prox = positions_proximity(head.position, next_position);
-
-                    if prox > 0 && prox < MAX_DISTANCE {
-                        word_pair_proximity
-                            .entry((head.word.clone(), head.word.clone()))
-                            .and_modify(|p| {
-                                *p = cmp::min(*p, prox);
-                            })
-                            .or_insert(prox);
-                    }
-
-                    word_positions_heap.push(PeekedWordPosition {
-                        word: head.word,
-                        position: next_position,
-                        iter: head.iter,
-                    });
-                }
-            }
-        }
-    }
 
+    let mut buffer = Vec::new();
     let mut key_buffer = Vec::new();
-    for ((w1, w2), prox) in word_pair_proximity {
+    for eob in
+        merge_join_by(del_word_pair_proximity.iter(), add_word_pair_proximity.iter(), |d, a| {
+            d.cmp(a)
+        })
+    {
+        buffer.clear();
+        let mut value_writer = KvWriterDelAdd::new(&mut buffer);
+        let ((w1, w2), prox) = match eob {
+            Left(key_value) => {
+                value_writer.insert(DelAdd::Deletion, document_id.to_ne_bytes()).unwrap();
+                key_value
+            }
+            Right(key_value) => {
+                value_writer.insert(DelAdd::Addition, document_id.to_ne_bytes()).unwrap();
+                key_value
+            }
+            Both(key_value, _) => {
+                value_writer.insert(DelAdd::Deletion, document_id.to_ne_bytes()).unwrap();
+                value_writer.insert(DelAdd::Addition, document_id.to_ne_bytes()).unwrap();
+                key_value
+            }
+        };
+
         key_buffer.clear();
-        key_buffer.push(prox as u8);
+        key_buffer.push(*prox);
         key_buffer.extend_from_slice(w1.as_bytes());
         key_buffer.push(0);
         key_buffer.extend_from_slice(w2.as_bytes());
 
-        word_pair_proximity_docids_sorter.insert(&key_buffer, document_id.to_ne_bytes())?;
+        word_pair_proximity_docids_sorters[*prox as usize - 1]
+            .insert(&key_buffer, value_writer.into_inner().unwrap())?;
     }
 
     Ok(())
 }
 
-struct PeekedWordPosition<I> {
+fn word_positions_into_word_pair_proximity(
-    word: String,
+    word_positions: &mut VecDeque<(String, u16)>,
-    position: u32,
+    word_pair_proximity: &mut BTreeMap<(String, String), u8>,
-    iter: I,
+) -> Result<()> {
-}
+    let (head_word, head_position) = word_positions.pop_front().unwrap();
-
+    for (word, position) in word_positions.iter() {
-impl<I> Ord for PeekedWordPosition<I> {
+        let prox = index_proximity(head_position as u32, *position as u32) as u8;
-    fn cmp(&self, other: &Self) -> Ordering {
+        if prox > 0 && prox < MAX_DISTANCE as u8 {
-        self.position.cmp(&other.position).reverse()
+            word_pair_proximity
-    }
+                .entry((head_word.clone(), word.clone()))
-}
+                .and_modify(|p| {
-
+                    *p = cmp::min(*p, prox);
-impl<I> PartialOrd for PeekedWordPosition<I> {
+                })
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+                .or_insert(prox);
-        Some(self.cmp(other))
+        }
-    }
-}
-
-impl<I> Eq for PeekedWordPosition<I> {}
-
-impl<I> PartialEq for PeekedWordPosition<I> {
-    fn eq(&self, other: &Self) -> bool {
-        self.position == other.position
     }
+    Ok(())
 }

milli/src/update/index_documents/extract/extract_word_position_docids.rs

@@ -1,13 +1,18 @@
+use std::collections::BTreeSet;
 use std::fs::File;
 use std::io::{self, BufReader};
 
+use obkv::KvReaderU16;
+
 use super::helpers::{
-    create_sorter, merge_cbo_roaring_bitmaps, read_u32_ne_bytes, sorter_into_reader,
+    create_sorter, merge_deladd_cbo_roaring_bitmaps, sorter_into_reader, try_split_array_at,
-    try_split_array_at, GrenadParameters,
+    GrenadParameters,
 };
 use crate::error::SerializationError;
 use crate::index::db_name::DOCID_WORD_POSITIONS;
-use crate::{bucketed_position, relative_from_absolute_position, DocumentId, Result};
+use crate::update::del_add::{DelAdd, KvReaderDelAdd, KvWriterDelAdd};
+use crate::update::MergeFn;
+use crate::{bucketed_position, DocumentId, Result};
 
 /// Extracts the word positions and the documents ids where this word appear.
 ///
@@ -24,32 +29,111 @@ pub fn extract_word_position_docids<R: io::Read + io::Seek>(
 
     let mut word_position_docids_sorter = create_sorter(
         grenad::SortAlgorithm::Unstable,
-        merge_cbo_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
         indexer.max_nb_chunks,
         max_memory,
     );
 
+    let mut del_word_positions: BTreeSet<(u16, Vec<u8>)> = BTreeSet::new();
+    let mut add_word_positions: BTreeSet<(u16, Vec<u8>)> = BTreeSet::new();
+    let mut current_document_id: Option<u32> = None;
     let mut key_buffer = Vec::new();
     let mut cursor = docid_word_positions.into_cursor()?;
     while let Some((key, value)) = cursor.move_on_next()? {
-        let (document_id_bytes, word_bytes) = try_split_array_at(key)
+        let (document_id_bytes, _fid_bytes) = try_split_array_at(key)
             .ok_or(SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
         let document_id = DocumentId::from_be_bytes(document_id_bytes);
 
-        for position in read_u32_ne_bytes(value) {
+        if current_document_id.map_or(false, |id| document_id != id) {
-            key_buffer.clear();
+            words_position_into_sorter(
-            key_buffer.extend_from_slice(word_bytes);
+                current_document_id.unwrap(),
-            key_buffer.push(0);
+                &mut key_buffer,
-            let (_, position) = relative_from_absolute_position(position);
+                &del_word_positions,
-            let position = bucketed_position(position);
+                &add_word_positions,
-            key_buffer.extend_from_slice(&position.to_be_bytes());
+                &mut word_position_docids_sorter,
-            word_position_docids_sorter.insert(&key_buffer, document_id.to_ne_bytes())?;
+            )?;
+            del_word_positions.clear();
+            add_word_positions.clear();
+        }
+
+        current_document_id = Some(document_id);
+
+        let del_add_reader = KvReaderDelAdd::new(value);
+        // extract all unique words to remove.
+        if let Some(deletion) = del_add_reader.get(DelAdd::Deletion) {
+            for (position, word_bytes) in KvReaderU16::new(deletion).iter() {
+                let position = bucketed_position(position);
+                del_word_positions.insert((position, word_bytes.to_vec()));
+            }
+        }
+
+        // extract all unique additional words.
+        if let Some(addition) = del_add_reader.get(DelAdd::Addition) {
+            for (position, word_bytes) in KvReaderU16::new(addition).iter() {
+                let position = bucketed_position(position);
+                add_word_positions.insert((position, word_bytes.to_vec()));
+            }
         }
     }
 
+    if let Some(document_id) = current_document_id {
+        words_position_into_sorter(
+            document_id,
+            &mut key_buffer,
+            &del_word_positions,
+            &add_word_positions,
+            &mut word_position_docids_sorter,
+        )?;
+    }
+
+    // TODO remove noop DelAdd OBKV
     let word_position_docids_reader = sorter_into_reader(word_position_docids_sorter, indexer)?;
 
     Ok(word_position_docids_reader)
 }
+
+fn words_position_into_sorter(
+    document_id: DocumentId,
+    key_buffer: &mut Vec<u8>,
+    del_word_positions: &BTreeSet<(u16, Vec<u8>)>,
+    add_word_positions: &BTreeSet<(u16, Vec<u8>)>,
+    word_position_docids_sorter: &mut grenad::Sorter<MergeFn>,
+) -> Result<()> {
+    puffin::profile_function!();
+
+    use itertools::merge_join_by;
+    use itertools::EitherOrBoth::{Both, Left, Right};
+
+    let mut buffer = Vec::new();
+    for eob in merge_join_by(del_word_positions.iter(), add_word_positions.iter(), |d, a| d.cmp(a))
+    {
+        buffer.clear();
+        let mut value_writer = KvWriterDelAdd::new(&mut buffer);
+        let (position, word_bytes) = match eob {
+            Left(key) => {
+                value_writer.insert(DelAdd::Deletion, document_id.to_ne_bytes()).unwrap();
+                key
+            }
+            Right(key) => {
+                value_writer.insert(DelAdd::Addition, document_id.to_ne_bytes()).unwrap();
+                key
+            }
+            Both(key, _) => {
+                // both values needs to be kept because it will be used in other extractors.
+                value_writer.insert(DelAdd::Deletion, document_id.to_ne_bytes()).unwrap();
+                value_writer.insert(DelAdd::Addition, document_id.to_ne_bytes()).unwrap();
+                key
+            }
+        };
+
+        key_buffer.clear();
+        key_buffer.extend_from_slice(word_bytes);
+        key_buffer.push(0);
+        key_buffer.extend_from_slice(&position.to_be_bytes());
+        word_position_docids_sorter.insert(&key_buffer, value_writer.into_inner().unwrap())?;
+    }
+
+    Ok(())
+}

milli/src/update/index_documents/extract/mod.rs

@@ -6,7 +6,6 @@ mod extract_fid_word_count_docids;
 mod extract_geo_points;
 mod extract_vector_points;
 mod extract_word_docids;
-mod extract_word_fid_docids;
 mod extract_word_pair_proximity_docids;
 mod extract_word_position_docids;
 
@@ -26,12 +25,11 @@ use self::extract_fid_word_count_docids::extract_fid_word_count_docids;
 use self::extract_geo_points::extract_geo_points;
 use self::extract_vector_points::extract_vector_points;
 use self::extract_word_docids::extract_word_docids;
-use self::extract_word_fid_docids::extract_word_fid_docids;
 use self::extract_word_pair_proximity_docids::extract_word_pair_proximity_docids;
 use self::extract_word_position_docids::extract_word_position_docids;
 use super::helpers::{
-    as_cloneable_grenad, merge_cbo_roaring_bitmaps, merge_roaring_bitmaps, CursorClonableMmap,
+    as_cloneable_grenad, merge_deladd_cbo_roaring_bitmaps, CursorClonableMmap, GrenadParameters,
-    GrenadParameters, MergeFn, MergeableReader,
+    MergeFn, MergeableReader,
 };
 use super::{helpers, TypedChunk};
 use crate::{FieldId, Result};
@@ -65,7 +63,6 @@ pub(crate) fn data_from_obkv_documents(
                 indexer,
                 lmdb_writer_sx.clone(),
                 vectors_field_id,
-                primary_key_id,
             )
         })
         .collect::<Result<()>>()?;
@@ -94,9 +91,9 @@ pub(crate) fn data_from_obkv_documents(
     let (
         docid_word_positions_chunks,
         (
-            docid_fid_facet_numbers_chunks,
+            fid_docid_facet_numbers_chunks,
             (
-                docid_fid_facet_strings_chunks,
+                fid_docid_facet_strings_chunks,
                 (
                     facet_is_null_docids_chunks,
                     (facet_is_empty_docids_chunks, facet_exists_docids_chunks),
@@ -110,7 +107,7 @@ pub(crate) fn data_from_obkv_documents(
         let lmdb_writer_sx = lmdb_writer_sx.clone();
         rayon::spawn(move || {
             debug!("merge {} database", "facet-id-exists-docids");
-            match facet_exists_docids_chunks.merge(merge_cbo_roaring_bitmaps, &indexer) {
+            match facet_exists_docids_chunks.merge(merge_deladd_cbo_roaring_bitmaps, &indexer) {
                 Ok(reader) => {
                     let _ = lmdb_writer_sx.send(Ok(TypedChunk::FieldIdFacetExistsDocids(reader)));
                 }
@@ -126,7 +123,7 @@ pub(crate) fn data_from_obkv_documents(
         let lmdb_writer_sx = lmdb_writer_sx.clone();
         rayon::spawn(move || {
             debug!("merge {} database", "facet-id-is-null-docids");
-            match facet_is_null_docids_chunks.merge(merge_cbo_roaring_bitmaps, &indexer) {
+            match facet_is_null_docids_chunks.merge(merge_deladd_cbo_roaring_bitmaps, &indexer) {
                 Ok(reader) => {
                     let _ = lmdb_writer_sx.send(Ok(TypedChunk::FieldIdFacetIsNullDocids(reader)));
                 }
@@ -142,7 +139,7 @@ pub(crate) fn data_from_obkv_documents(
         let lmdb_writer_sx = lmdb_writer_sx.clone();
         rayon::spawn(move || {
             debug!("merge {} database", "facet-id-is-empty-docids");
-            match facet_is_empty_docids_chunks.merge(merge_cbo_roaring_bitmaps, &indexer) {
+            match facet_is_empty_docids_chunks.merge(merge_deladd_cbo_roaring_bitmaps, &indexer) {
                 Ok(reader) => {
                     let _ = lmdb_writer_sx.send(Ok(TypedChunk::FieldIdFacetIsEmptyDocids(reader)));
                 }
@@ -158,7 +155,7 @@ pub(crate) fn data_from_obkv_documents(
         indexer,
         lmdb_writer_sx.clone(),
         extract_word_pair_proximity_docids,
-        merge_cbo_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
         TypedChunk::WordPairProximityDocids,
         "word-pair-proximity-docids",
     );
@@ -168,24 +165,31 @@ pub(crate) fn data_from_obkv_documents(
         indexer,
         lmdb_writer_sx.clone(),
         extract_fid_word_count_docids,
-        merge_cbo_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
-        TypedChunk::FieldIdWordcountDocids,
+        TypedChunk::FieldIdWordCountDocids,
         "field-id-wordcount-docids",
     );
 
     spawn_extraction_task::<
         _,
         _,
-        Vec<(grenad::Reader<BufReader<File>>, grenad::Reader<BufReader<File>>)>,
+        Vec<(
+            grenad::Reader<BufReader<File>>,
+            grenad::Reader<BufReader<File>>,
+            grenad::Reader<BufReader<File>>,
+        )>,
     >(
         docid_word_positions_chunks.clone(),
         indexer,
         lmdb_writer_sx.clone(),
         move |doc_word_pos, indexer| extract_word_docids(doc_word_pos, indexer, &exact_attributes),
-        merge_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
-        |(word_docids_reader, exact_word_docids_reader)| TypedChunk::WordDocids {
+        |(word_docids_reader, exact_word_docids_reader, word_fid_docids_reader)| {
-            word_docids_reader,
+            TypedChunk::WordDocids {
-            exact_word_docids_reader,
+                word_docids_reader,
+                exact_word_docids_reader,
+                word_fid_docids_reader,
+            }
         },
         "word-docids",
     );
@@ -195,36 +199,27 @@ pub(crate) fn data_from_obkv_documents(
         indexer,
         lmdb_writer_sx.clone(),
         extract_word_position_docids,
-        merge_cbo_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
         TypedChunk::WordPositionDocids,
         "word-position-docids",
     );
-    spawn_extraction_task::<_, _, Vec<grenad::Reader<BufReader<File>>>>(
-        docid_word_positions_chunks,
-        indexer,
-        lmdb_writer_sx.clone(),
-        extract_word_fid_docids,
-        merge_cbo_roaring_bitmaps,
-        TypedChunk::WordFidDocids,
-        "word-fid-docids",
-    );
 
     spawn_extraction_task::<_, _, Vec<grenad::Reader<BufReader<File>>>>(
-        docid_fid_facet_strings_chunks,
+        fid_docid_facet_strings_chunks,
         indexer,
         lmdb_writer_sx.clone(),
         extract_facet_string_docids,
-        merge_cbo_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
         TypedChunk::FieldIdFacetStringDocids,
         "field-id-facet-string-docids",
     );
 
     spawn_extraction_task::<_, _, Vec<grenad::Reader<BufReader<File>>>>(
-        docid_fid_facet_numbers_chunks,
+        fid_docid_facet_numbers_chunks,
         indexer,
         lmdb_writer_sx,
         extract_facet_number_docids,
-        merge_cbo_roaring_bitmaps,
+        merge_deladd_cbo_roaring_bitmaps,
         TypedChunk::FieldIdFacetNumberDocids,
         "field-id-facet-number-docids",
     );
@@ -278,7 +273,6 @@ fn send_original_documents_data(
     indexer: GrenadParameters,
     lmdb_writer_sx: Sender<Result<TypedChunk>>,
     vectors_field_id: Option<FieldId>,
-    primary_key_id: FieldId,
 ) -> Result<()> {
     let original_documents_chunk =
         original_documents_chunk.and_then(|c| unsafe { as_cloneable_grenad(&c) })?;
@@ -287,12 +281,7 @@ fn send_original_documents_data(
         let documents_chunk_cloned = original_documents_chunk.clone();
         let lmdb_writer_sx_cloned = lmdb_writer_sx.clone();
         rayon::spawn(move || {
-            let result = extract_vector_points(
+            let result = extract_vector_points(documents_chunk_cloned, indexer, vectors_field_id);
-                documents_chunk_cloned,
-                indexer,
-                primary_key_id,
-                vectors_field_id,
-            );
             let _ = match result {
                 Ok(vector_points) => {
                     lmdb_writer_sx_cloned.send(Ok(TypedChunk::VectorPoints(vector_points)))
@@ -356,10 +345,10 @@ fn send_and_extract_flattened_documents_data(
         });
     }
 
-    let (docid_word_positions_chunk, docid_fid_facet_values_chunks): (Result<_>, Result<_>) =
+    let (docid_word_positions_chunk, fid_docid_facet_values_chunks): (Result<_>, Result<_>) =
         rayon::join(
             || {
-                let (documents_ids, docid_word_positions_chunk, script_language_pair) =
+                let (docid_word_positions_chunk, script_language_pair) =
                     extract_docid_word_positions(
                         flattened_documents_chunk.clone(),
                         indexer,
@@ -370,9 +359,6 @@ fn send_and_extract_flattened_documents_data(
                         max_positions_per_attributes,
                     )?;
 
-                // send documents_ids to DB writer
-                let _ = lmdb_writer_sx.send(Ok(TypedChunk::NewDocumentsIds(documents_ids)));
-
                 // send docid_word_positions_chunk to DB writer
                 let docid_word_positions_chunk =
                     unsafe { as_cloneable_grenad(&docid_word_positions_chunk)? };
@@ -384,8 +370,8 @@ fn send_and_extract_flattened_documents_data(
             },
             || {
                 let ExtractedFacetValues {
-                    docid_fid_facet_numbers_chunk,
+                    fid_docid_facet_numbers_chunk,
-                    docid_fid_facet_strings_chunk,
+                    fid_docid_facet_strings_chunk,
                     fid_facet_is_null_docids_chunk,
                     fid_facet_is_empty_docids_chunk,
                     fid_facet_exists_docids_chunk,
@@ -396,26 +382,26 @@ fn send_and_extract_flattened_documents_data(
                     geo_fields_ids,
                 )?;
 
-                // send docid_fid_facet_numbers_chunk to DB writer
+                // send fid_docid_facet_numbers_chunk to DB writer
-                let docid_fid_facet_numbers_chunk =
+                let fid_docid_facet_numbers_chunk =
-                    unsafe { as_cloneable_grenad(&docid_fid_facet_numbers_chunk)? };
+                    unsafe { as_cloneable_grenad(&fid_docid_facet_numbers_chunk)? };
 
                 let _ = lmdb_writer_sx.send(Ok(TypedChunk::FieldIdDocidFacetNumbers(
-                    docid_fid_facet_numbers_chunk.clone(),
+                    fid_docid_facet_numbers_chunk.clone(),
                 )));
 
-                // send docid_fid_facet_strings_chunk to DB writer
+                // send fid_docid_facet_strings_chunk to DB writer
-                let docid_fid_facet_strings_chunk =
+                let fid_docid_facet_strings_chunk =
-                    unsafe { as_cloneable_grenad(&docid_fid_facet_strings_chunk)? };
+                    unsafe { as_cloneable_grenad(&fid_docid_facet_strings_chunk)? };
 
                 let _ = lmdb_writer_sx.send(Ok(TypedChunk::FieldIdDocidFacetStrings(
-                    docid_fid_facet_strings_chunk.clone(),
+                    fid_docid_facet_strings_chunk.clone(),
                 )));
 
                 Ok((
-                    docid_fid_facet_numbers_chunk,
+                    fid_docid_facet_numbers_chunk,
                     (
-                        docid_fid_facet_strings_chunk,
+                        fid_docid_facet_strings_chunk,
                         (
                             fid_facet_is_null_docids_chunk,
                             (fid_facet_is_empty_docids_chunk, fid_facet_exists_docids_chunk),
@@ -425,5 +411,5 @@ fn send_and_extract_flattened_documents_data(
             },
         );
 
-    Ok((docid_word_positions_chunk?, docid_fid_facet_values_chunks?))
+    Ok((docid_word_positions_chunk?, fid_docid_facet_values_chunks?))
 }

milli/src/update/index_documents/helpers/grenad_helpers.rs

@@ -1,14 +1,12 @@
 use std::borrow::Cow;
 use std::fs::File;
 use std::io::{self, BufReader, BufWriter, Seek};
-use std::time::Instant;
 
 use grenad::{CompressionType, Sorter};
 use heed::types::ByteSlice;
-use log::debug;
 
 use super::{ClonableMmap, MergeFn};
-use crate::error::InternalError;
+use crate::update::index_documents::valid_lmdb_key;
 use crate::Result;
 
 pub type CursorClonableMmap = io::Cursor<ClonableMmap>;
@@ -47,6 +45,7 @@ pub fn create_sorter(
         builder.allow_realloc(false);
     }
     builder.sort_algorithm(sort_algorithm);
+    builder.sort_in_parallel(true);
     builder.build()
 }
 
@@ -54,6 +53,7 @@ pub fn sorter_into_reader(
     sorter: grenad::Sorter<MergeFn>,
     indexer: GrenadParameters,
 ) -> Result<grenad::Reader<BufReader<File>>> {
+    puffin::profile_function!();
     let mut writer = create_writer(
         indexer.chunk_compression_type,
         indexer.chunk_compression_level,
@@ -115,6 +115,32 @@ impl MergeableReader for Vec<(grenad::Reader<BufReader<File>>, grenad::Reader<Bu
     }
 }
 
+impl MergeableReader
+    for Vec<(
+        grenad::Reader<BufReader<File>>,
+        grenad::Reader<BufReader<File>>,
+        grenad::Reader<BufReader<File>>,
+    )>
+{
+    type Output = (
+        grenad::Reader<BufReader<File>>,
+        grenad::Reader<BufReader<File>>,
+        grenad::Reader<BufReader<File>>,
+    );
+
+    fn merge(self, merge_fn: MergeFn, params: &GrenadParameters) -> Result<Self::Output> {
+        let mut m1 = MergerBuilder::new(merge_fn);
+        let mut m2 = MergerBuilder::new(merge_fn);
+        let mut m3 = MergerBuilder::new(merge_fn);
+        for (r1, r2, r3) in self.into_iter() {
+            m1.push(r1)?;
+            m2.push(r2)?;
+            m3.push(r3)?;
+        }
+        Ok((m1.finish(params)?, m2.finish(params)?, m3.finish(params)?))
+    }
+}
+
 struct MergerBuilder<R>(grenad::MergerBuilder<R, MergeFn>);
 
 impl<R: io::Read + io::Seek> MergerBuilder<R> {
@@ -195,11 +221,13 @@ pub fn grenad_obkv_into_chunks<R: io::Read + io::Seek>(
         );
 
         while let Some((document_id, obkv)) = cursor.move_on_next()? {
-            obkv_documents.insert(document_id, obkv)?;
+            if !obkv.is_empty() {
-            current_chunk_size += document_id.len() as u64 + obkv.len() as u64;
+                obkv_documents.insert(document_id, obkv)?;
+                current_chunk_size += document_id.len() as u64 + obkv.len() as u64;
 
-            if current_chunk_size >= documents_chunk_size as u64 {
+                if current_chunk_size >= documents_chunk_size as u64 {
-                return writer_into_reader(obkv_documents).map(Some);
+                    return writer_into_reader(obkv_documents).map(Some);
+                }
             }
         }
 
@@ -210,45 +238,46 @@ pub fn grenad_obkv_into_chunks<R: io::Read + io::Seek>(
     Ok(std::iter::from_fn(move || transposer().transpose()))
 }
 
-pub fn sorter_into_lmdb_database(
+/// Write provided sorter in database using serialize_value function.
-    wtxn: &mut heed::RwTxn,
+/// merge_values function is used if an entry already exist in the database.
-    database: heed::PolyDatabase,
+pub fn write_sorter_into_database<K, V, FS, FM>(
     sorter: Sorter<MergeFn>,
-    merge: MergeFn,
+    database: &heed::Database<K, V>,
-) -> Result<()> {
+    wtxn: &mut heed::RwTxn,
+    index_is_empty: bool,
+    serialize_value: FS,
+    merge_values: FM,
+) -> Result<()>
+where
+    FS: for<'a> Fn(&'a [u8], &'a mut Vec<u8>) -> Result<&'a [u8]>,
+    FM: for<'a> Fn(&[u8], &[u8], &'a mut Vec<u8>) -> Result<Option<&'a [u8]>>,
+{
     puffin::profile_function!();
-    debug!("Writing MTBL sorter...");
+
-    let before = Instant::now();
+    let mut buffer = Vec::new();
+    let database = database.remap_types::<ByteSlice, ByteSlice>();
 
     let mut merger_iter = sorter.into_stream_merger_iter()?;
-    if database.is_empty(wtxn)? {
+    while let Some((key, value)) = merger_iter.next()? {
-        let mut out_iter = database.iter_mut::<_, ByteSlice, ByteSlice>(wtxn)?;
+        if valid_lmdb_key(key) {
-        while let Some((k, v)) = merger_iter.next()? {
+            buffer.clear();
-            // safety: we don't keep references from inside the LMDB database.
+            let value = if index_is_empty {
-            unsafe { out_iter.append(k, v)? };
+                Some(serialize_value(value, &mut buffer)?)
-        }
+            } else {
-    } else {
+                match database.get(wtxn, key)? {
-        while let Some((k, v)) = merger_iter.next()? {
+                    Some(prev_value) => merge_values(value, prev_value, &mut buffer)?,
-            let mut iter = database.prefix_iter_mut::<_, ByteSlice, ByteSlice>(wtxn, k)?;
+                    None => Some(serialize_value(value, &mut buffer)?),
-            match iter.next().transpose()? {
-                Some((key, old_val)) if key == k => {
-                    let vals = vec![Cow::Borrowed(old_val), Cow::Borrowed(v)];
-                    let val = merge(k, &vals).map_err(|_| {
-                        // TODO just wrap this error?
-                        InternalError::IndexingMergingKeys { process: "get-put-merge" }
-                    })?;
-                    // safety: we don't keep references from inside the LMDB database.
-                    unsafe { iter.put_current(k, &val)? };
                 }
-                _ => {
+            };
-                    drop(iter);
+            match value {
-                    database.put::<_, ByteSlice, ByteSlice>(wtxn, k, v)?;
+                Some(value) => database.put(wtxn, key, value)?,
+                None => {
+                    database.delete(wtxn, key)?;
                 }
             }
         }
     }
 
-    debug!("MTBL sorter writen in {:.02?}!", before.elapsed());
     Ok(())
 }
 

milli/src/update/index_documents/helpers/merge_functions.rs

@@ -6,22 +6,12 @@ use std::result::Result as StdResult;
 use roaring::RoaringBitmap;
 
 use crate::heed_codec::CboRoaringBitmapCodec;
+use crate::update::del_add::{DelAdd, KvReaderDelAdd, KvWriterDelAdd};
 use crate::update::index_documents::transform::Operation;
 use crate::Result;
 
 pub type MergeFn = for<'a> fn(&[u8], &[Cow<'a, [u8]>]) -> Result<Cow<'a, [u8]>>;
 
-pub fn concat_u32s_array<'a>(_key: &[u8], values: &[Cow<'a, [u8]>]) -> Result<Cow<'a, [u8]>> {
-    if values.len() == 1 {
-        Ok(values[0].clone())
-    } else {
-        let capacity = values.iter().map(|v| v.len()).sum::<usize>();
-        let mut output = Vec::with_capacity(capacity);
-        values.iter().for_each(|integers| output.extend_from_slice(integers));
-        Ok(Cow::Owned(output))
-    }
-}
-
 pub fn serialize_roaring_bitmap(bitmap: &RoaringBitmap, buffer: &mut Vec<u8>) -> io::Result<()> {
     buffer.clear();
     buffer.reserve(bitmap.serialized_size());
@@ -75,57 +65,123 @@ pub fn keep_latest_obkv<'a>(_key: &[u8], obkvs: &[Cow<'a, [u8]>]) -> Result<Cow<
     Ok(obkvs.last().unwrap().clone())
 }
 
-pub fn merge_two_obkvs(base: obkv::KvReaderU16, update: obkv::KvReaderU16, buffer: &mut Vec<u8>) {
+pub fn merge_two_del_add_obkvs(
+    base: obkv::KvReaderU16,
+    update: obkv::KvReaderU16,
+    merge_additions: bool,
+    buffer: &mut Vec<u8>,
+) {
     use itertools::merge_join_by;
     use itertools::EitherOrBoth::{Both, Left, Right};
 
     buffer.clear();
 
     let mut writer = obkv::KvWriter::new(buffer);
+    let mut value_buffer = Vec::new();
     for eob in merge_join_by(base.iter(), update.iter(), |(b, _), (u, _)| b.cmp(u)) {
         match eob {
-            Both(_, (k, v)) | Left((k, v)) | Right((k, v)) => writer.insert(k, v).unwrap(),
+            Left((k, v)) => {
+                if merge_additions {
+                    writer.insert(k, v).unwrap()
+                } else {
+                    // If merge_additions is false, recreate an obkv keeping the deletions only.
+                    value_buffer.clear();
+                    let mut value_writer = KvWriterDelAdd::new(&mut value_buffer);
+                    let base_reader = KvReaderDelAdd::new(v);
+
+                    if let Some(deletion) = base_reader.get(DelAdd::Deletion) {
+                        value_writer.insert(DelAdd::Deletion, deletion).unwrap();
+                        value_writer.finish().unwrap();
+                        writer.insert(k, &value_buffer).unwrap()
+                    }
+                }
+            }
+            Right((k, v)) => writer.insert(k, v).unwrap(),
+            Both((k, base), (_, update)) => {
+                // merge deletions and additions.
+                value_buffer.clear();
+                let mut value_writer = KvWriterDelAdd::new(&mut value_buffer);
+                let base_reader = KvReaderDelAdd::new(base);
+                let update_reader = KvReaderDelAdd::new(update);
+
+                // keep newest deletion.
+                if let Some(deletion) = update_reader
+                    .get(DelAdd::Deletion)
+                    .or_else(|| base_reader.get(DelAdd::Deletion))
+                {
+                    value_writer.insert(DelAdd::Deletion, deletion).unwrap();
+                }
+
+                // keep base addition only if merge_additions is true.
+                let base_addition =
+                    merge_additions.then(|| base_reader.get(DelAdd::Addition)).flatten();
+                // keep newest addition.
+                // TODO use or_else
+                if let Some(addition) = update_reader.get(DelAdd::Addition).or(base_addition) {
+                    value_writer.insert(DelAdd::Addition, addition).unwrap();
+                }
+
+                value_writer.finish().unwrap();
+                writer.insert(k, &value_buffer).unwrap()
+            }
         }
     }
 
     writer.finish().unwrap();
 }
 
-/// Merge all the obks in the order we see them.
+/// Merge all the obkvs from the newest to the oldest.
-pub fn merge_obkvs_and_operations<'a>(
+fn inner_merge_del_add_obkvs<'a>(
+    obkvs: &[Cow<'a, [u8]>],
+    merge_additions: bool,
+) -> Result<Cow<'a, [u8]>> {
+    // pop the newest operation from the list.
+    let (newest, obkvs) = obkvs.split_last().unwrap();
+    // keep the operation type for the returned value.
+    let newest_operation_type = newest[0];
+
+    // treat the newest obkv as the starting point of the merge.
+    let mut acc_operation_type = newest_operation_type;
+    let mut acc = newest[1..].to_vec();
+    let mut buffer = Vec::new();
+    // reverse iter from the most recent to the oldest.
+    for current in obkvs.iter().rev() {
+        // if in the previous iteration there was a complete deletion,
+        // stop the merge process.
+        if acc_operation_type == Operation::Deletion as u8 {
+            break;
+        }
+
+        let newest = obkv::KvReader::new(&acc);
+        let oldest = obkv::KvReader::new(&current[1..]);
+        merge_two_del_add_obkvs(oldest, newest, merge_additions, &mut buffer);
+
+        // we want the result of the merge into our accumulator.
+        std::mem::swap(&mut acc, &mut buffer);
+        acc_operation_type = current[0];
+    }
+
+    acc.insert(0, newest_operation_type);
+    Ok(Cow::from(acc))
+}
+
+/// Merge all the obkvs from the newest to the oldest.
+pub fn obkvs_merge_additions_and_deletions<'a>(
     _key: &[u8],
     obkvs: &[Cow<'a, [u8]>],
 ) -> Result<Cow<'a, [u8]>> {
-    // [add, add, delete, add, add]
+    inner_merge_del_add_obkvs(obkvs, true)
-    // we can ignore everything that happened before the last delete.
-    let starting_position =
-        obkvs.iter().rposition(|obkv| obkv[0] == Operation::Deletion as u8).unwrap_or(0);
-
-    // [add, add, delete]
-    // if the last operation was a deletion then we simply return the deletion
-    if starting_position == obkvs.len() - 1 && obkvs.last().unwrap()[0] == Operation::Deletion as u8
-    {
-        return Ok(obkvs[obkvs.len() - 1].clone());
-    }
-    let mut buffer = Vec::new();
-
-    // (add, add, delete) [add, add]
-    // in the other case, no deletion will be encountered during the merge
-    let mut ret =
-        obkvs[starting_position..].iter().cloned().fold(Vec::new(), |mut acc, current| {
-            let first = obkv::KvReader::new(&acc);
-            let second = obkv::KvReader::new(&current[1..]);
-            merge_two_obkvs(first, second, &mut buffer);
-
-            // we want the result of the merge into our accumulator
-            std::mem::swap(&mut acc, &mut buffer);
-            acc
-        });
-
-    ret.insert(0, Operation::Addition as u8);
-    Ok(Cow::from(ret))
 }
 
+/// Merge all the obkvs deletions from the newest to the oldest and keep only the newest additions.
+pub fn obkvs_keep_last_addition_merge_deletions<'a>(
+    _key: &[u8],
+    obkvs: &[Cow<'a, [u8]>],
+) -> Result<Cow<'a, [u8]>> {
+    inner_merge_del_add_obkvs(obkvs, false)
+}
+
+/// Do a union of all the CboRoaringBitmaps in the values.
 pub fn merge_cbo_roaring_bitmaps<'a>(
     _key: &[u8],
     values: &[Cow<'a, [u8]>],
@@ -138,3 +194,52 @@ pub fn merge_cbo_roaring_bitmaps<'a>(
         Ok(Cow::from(vec))
     }
 }
+
+/// Do a union of CboRoaringBitmaps on both sides of a DelAdd obkv
+/// separately and outputs a new DelAdd with both unions.
+pub fn merge_deladd_cbo_roaring_bitmaps<'a>(
+    _key: &[u8],
+    values: &[Cow<'a, [u8]>],
+) -> Result<Cow<'a, [u8]>> {
+    if values.len() == 1 {
+        Ok(values[0].clone())
+    } else {
+        // Retrieve the bitmaps from both sides
+        let mut del_bitmaps_bytes = Vec::new();
+        let mut add_bitmaps_bytes = Vec::new();
+        for value in values {
+            let obkv = KvReaderDelAdd::new(value);
+            if let Some(bitmap_bytes) = obkv.get(DelAdd::Deletion) {
+                del_bitmaps_bytes.push(bitmap_bytes);
+            }
+            if let Some(bitmap_bytes) = obkv.get(DelAdd::Addition) {
+                add_bitmaps_bytes.push(bitmap_bytes);
+            }
+        }
+
+        let mut output_deladd_obkv = KvWriterDelAdd::memory();
+        let mut buffer = Vec::new();
+        CboRoaringBitmapCodec::merge_into(del_bitmaps_bytes, &mut buffer)?;
+        output_deladd_obkv.insert(DelAdd::Deletion, &buffer)?;
+        buffer.clear();
+        CboRoaringBitmapCodec::merge_into(add_bitmaps_bytes, &mut buffer)?;
+        output_deladd_obkv.insert(DelAdd::Addition, &buffer)?;
+        output_deladd_obkv.into_inner().map(Cow::from).map_err(Into::into)
+    }
+}
+
+/// A function that merges a DelAdd of bitmao into an already existing bitmap.
+///
+/// The first argument is the DelAdd obkv of CboRoaringBitmaps and
+/// the second one is the CboRoaringBitmap to merge into.
+pub fn merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap<'a>(
+    deladd_obkv: &[u8],
+    previous: &[u8],
+    buffer: &'a mut Vec<u8>,
+) -> Result<Option<&'a [u8]>> {
+    Ok(CboRoaringBitmapCodec::merge_deladd_into(
+        KvReaderDelAdd::new(deladd_obkv),
+        previous,
+        buffer,
+    )?)
+}

milli/src/update/index_documents/helpers/mod.rs

@@ -9,13 +9,14 @@ pub use clonable_mmap::{ClonableMmap, CursorClonableMmap};
 use fst::{IntoStreamer, Streamer};
 pub use grenad_helpers::{
     as_cloneable_grenad, create_sorter, create_writer, grenad_obkv_into_chunks,
-    merge_ignore_values, sorter_into_lmdb_database, sorter_into_reader, writer_into_reader,
+    merge_ignore_values, sorter_into_reader, write_sorter_into_database, writer_into_reader,
     GrenadParameters, MergeableReader,
 };
 pub use merge_functions::{
-    concat_u32s_array, keep_first, keep_latest_obkv, merge_btreeset_string,
+    keep_first, keep_latest_obkv, merge_btreeset_string, merge_cbo_roaring_bitmaps,
-    merge_cbo_roaring_bitmaps, merge_obkvs_and_operations, merge_roaring_bitmaps, merge_two_obkvs,
+    merge_deladd_cbo_roaring_bitmaps, merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
-    serialize_roaring_bitmap, MergeFn,
+    merge_roaring_bitmaps, obkvs_keep_last_addition_merge_deletions,
+    obkvs_merge_additions_and_deletions, serialize_roaring_bitmap, MergeFn,
 };
 
 use crate::MAX_WORD_LENGTH;
@@ -44,10 +45,6 @@ where
     Some((head, tail))
 }
 
-pub fn read_u32_ne_bytes(bytes: &[u8]) -> impl Iterator<Item = u32> + '_ {
-    bytes.chunks_exact(4).flat_map(TryInto::try_into).map(u32::from_ne_bytes)
-}
-
 /// Converts an fst Stream into an HashSet of Strings.
 pub fn fst_stream_into_hashset<'f, I, S>(stream: I) -> HashSet<Vec<u8>>
 where

milli/src/update/index_documents/mod.rs

@@ -20,14 +20,13 @@ use slice_group_by::GroupBy;
 use typed_chunk::{write_typed_chunk_into_index, TypedChunk};
 
 use self::enrich::enrich_documents_batch;
-pub use self::enrich::{
+pub use self::enrich::{extract_finite_float_from_value, validate_geo_from_json, DocumentId};
-    extract_finite_float_from_value, validate_document_id, validate_document_id_value,
-    validate_geo_from_json, DocumentId,
-};
 pub use self::helpers::{
     as_cloneable_grenad, create_sorter, create_writer, fst_stream_into_hashset,
-    fst_stream_into_vec, merge_btreeset_string, merge_cbo_roaring_bitmaps, merge_roaring_bitmaps,
+    fst_stream_into_vec, merge_btreeset_string, merge_cbo_roaring_bitmaps,
-    sorter_into_lmdb_database, valid_lmdb_key, writer_into_reader, ClonableMmap, MergeFn,
+    merge_deladd_cbo_roaring_bitmaps, merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
+    merge_roaring_bitmaps, valid_lmdb_key, write_sorter_into_database, writer_into_reader,
+    ClonableMmap, MergeFn,
 };
 use self::helpers::{grenad_obkv_into_chunks, GrenadParameters};
 pub use self::transform::{Transform, TransformOutput};
@@ -35,13 +34,12 @@ use crate::documents::{obkv_to_object, DocumentsBatchReader};
 use crate::error::{Error, InternalError, UserError};
 pub use crate::update::index_documents::helpers::CursorClonableMmap;
 use crate::update::{
-    self, DeletionStrategy, IndexerConfig, PrefixWordPairsProximityDocids, UpdateIndexingStep,
+    IndexerConfig, UpdateIndexingStep, WordPrefixDocids, WordPrefixIntegerDocids, WordsPrefixesFst,
-    WordPrefixDocids, WordPrefixIntegerDocids, WordsPrefixesFst,
 };
-use crate::{Index, Result, RoaringBitmapCodec};
+use crate::{CboRoaringBitmapCodec, Index, Result};
 
 static MERGED_DATABASE_COUNT: usize = 7;
-static PREFIX_DATABASE_COUNT: usize = 5;
+static PREFIX_DATABASE_COUNT: usize = 4;
 static TOTAL_POSTING_DATABASE_COUNT: usize = MERGED_DATABASE_COUNT + PREFIX_DATABASE_COUNT;
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
@@ -89,7 +87,6 @@ pub struct IndexDocumentsConfig {
     pub words_positions_level_group_size: Option<NonZeroU32>,
     pub words_positions_min_level_size: Option<NonZeroU32>,
     pub update_method: IndexDocumentsMethod,
-    pub deletion_strategy: DeletionStrategy,
     pub autogenerate_docids: bool,
 }
 
@@ -181,6 +178,7 @@ where
 
         // Early return when there is no document to add
         if to_delete.is_empty() {
+            // Maintains Invariant: remove documents actually always returns Ok for the inner result
             return Ok((self, Ok(0)));
         }
 
@@ -193,14 +191,48 @@ where
 
         self.deleted_documents += deleted_documents;
 
+        // Maintains Invariant: remove documents actually always returns Ok for the inner result
         Ok((self, Ok(deleted_documents)))
     }
 
+    /// Removes documents from db using their internal document ids.
+    ///
+    /// # Warning
+    ///
+    /// This function is dangerous and will only work correctly if:
+    ///
+    /// - All the passed ids currently exist in the database
+    /// - No batching using the standards `remove_documents` and `add_documents` took place
+    ///
+    /// TODO: make it impossible to call `remove_documents` or `add_documents` on an instance that calls this function.
+    pub fn remove_documents_from_db_no_batch(
+        mut self,
+        to_delete: &RoaringBitmap,
+    ) -> Result<(Self, u64)> {
+        puffin::profile_function!();
+
+        // Early return when there is no document to add
+        if to_delete.is_empty() {
+            return Ok((self, 0));
+        }
+
+        let deleted_documents = self
+            .transform
+            .as_mut()
+            .expect("Invalid document deletion state")
+            .remove_documents_from_db_no_batch(to_delete, self.wtxn, &self.should_abort)?
+            as u64;
+
+        self.deleted_documents += deleted_documents;
+
+        Ok((self, deleted_documents))
+    }
+
     #[logging_timer::time("IndexDocuments::{}")]
     pub fn execute(mut self) -> Result<DocumentAdditionResult> {
         puffin::profile_function!();
 
-        if self.added_documents == 0 {
+        if self.added_documents == 0 && self.deleted_documents == 0 {
             let number_of_documents = self.index.number_of_documents(self.wtxn)?;
             return Ok(DocumentAdditionResult { indexed_documents: 0, number_of_documents });
         }
@@ -244,9 +276,6 @@ where
             primary_key,
             fields_ids_map,
             field_distribution,
-            new_external_documents_ids,
-            new_documents_ids,
-            replaced_documents_ids,
             documents_count,
             original_documents,
             flattened_documents,
@@ -370,29 +399,12 @@ where
                 let _ = lmdb_writer_sx.send(Err(e));
             }
 
-            // needs to be droped to avoid channel waiting lock.
+            // needs to be dropped to avoid channel waiting lock.
             drop(lmdb_writer_sx)
         });
 
-        // We delete the documents that this document addition replaces. This way we are
+        let index_is_empty = self.index.number_of_documents(self.wtxn)? == 0;
-        // able to simply insert all the documents even if they already exist in the database.
-        if !replaced_documents_ids.is_empty() {
-            let mut deletion_builder = update::DeleteDocuments::new(self.wtxn, self.index)?;
-            deletion_builder.strategy(self.config.deletion_strategy);
-            debug!("documents to delete {:?}", replaced_documents_ids);
-            deletion_builder.delete_documents(&replaced_documents_ids);
-            let deleted_documents_result = deletion_builder.execute_inner()?;
-            debug!("{} documents actually deleted", deleted_documents_result.deleted_documents);
-        }
-
-        let index_documents_ids = self.index.documents_ids(self.wtxn)?;
-        let index_is_empty = index_documents_ids.is_empty();
         let mut final_documents_ids = RoaringBitmap::new();
-        let mut word_pair_proximity_docids = None;
-        let mut word_position_docids = None;
-        let mut word_fid_docids = None;
-        let mut word_docids = None;
-        let mut exact_word_docids = None;
 
         let mut databases_seen = 0;
         (self.progress)(UpdateIndexingStep::MergeDataIntoFinalDatabase {
@@ -400,35 +412,40 @@ where
             total_databases: TOTAL_POSTING_DATABASE_COUNT,
         });
 
+        let mut word_position_docids = None;
+        let mut word_fid_docids = None;
+        let mut word_docids = None;
+        let mut exact_word_docids = None;
+
         for result in lmdb_writer_rx {
             if (self.should_abort)() {
                 return Err(Error::InternalError(InternalError::AbortedIndexation));
             }
 
             let typed_chunk = match result? {
-                TypedChunk::WordDocids { word_docids_reader, exact_word_docids_reader } => {
+                TypedChunk::WordDocids {
+                    word_docids_reader,
+                    exact_word_docids_reader,
+                    word_fid_docids_reader,
+                } => {
                     let cloneable_chunk = unsafe { as_cloneable_grenad(&word_docids_reader)? };
                     word_docids = Some(cloneable_chunk);
                     let cloneable_chunk =
                         unsafe { as_cloneable_grenad(&exact_word_docids_reader)? };
                     exact_word_docids = Some(cloneable_chunk);
-                    TypedChunk::WordDocids { word_docids_reader, exact_word_docids_reader }
+                    let cloneable_chunk = unsafe { as_cloneable_grenad(&word_fid_docids_reader)? };
-                }
+                    word_fid_docids = Some(cloneable_chunk);
-                TypedChunk::WordPairProximityDocids(chunk) => {
+                    TypedChunk::WordDocids {
-                    let cloneable_chunk = unsafe { as_cloneable_grenad(&chunk)? };
+                        word_docids_reader,
-                    word_pair_proximity_docids = Some(cloneable_chunk);
+                        exact_word_docids_reader,
-                    TypedChunk::WordPairProximityDocids(chunk)
+                        word_fid_docids_reader,
+                    }
                 }
                 TypedChunk::WordPositionDocids(chunk) => {
                     let cloneable_chunk = unsafe { as_cloneable_grenad(&chunk)? };
                     word_position_docids = Some(cloneable_chunk);
                     TypedChunk::WordPositionDocids(chunk)
                 }
-                TypedChunk::WordFidDocids(chunk) => {
-                    let cloneable_chunk = unsafe { as_cloneable_grenad(&chunk)? };
-                    word_fid_docids = Some(cloneable_chunk);
-                    TypedChunk::WordFidDocids(chunk)
-                }
                 otherwise => otherwise,
             };
 
@@ -460,25 +477,16 @@ where
 
         // We write the primary key field id into the main database
         self.index.put_primary_key(self.wtxn, &primary_key)?;
-
+        let number_of_documents = self.index.number_of_documents(self.wtxn)?;
-        // We write the external documents ids into the main database.
-        let mut external_documents_ids = self.index.external_documents_ids(self.wtxn)?;
-        external_documents_ids.insert_ids(&new_external_documents_ids)?;
-        let external_documents_ids = external_documents_ids.into_static();
-        self.index.put_external_documents_ids(self.wtxn, &external_documents_ids)?;
-
-        let all_documents_ids = index_documents_ids | new_documents_ids;
-        self.index.put_documents_ids(self.wtxn, &all_documents_ids)?;
 
         self.execute_prefix_databases(
             word_docids,
             exact_word_docids,
-            word_pair_proximity_docids,
             word_position_docids,
             word_fid_docids,
         )?;
 
-        Ok(all_documents_ids.len())
+        Ok(number_of_documents)
     }
 
     #[logging_timer::time("IndexDocuments::{}")]
@@ -486,7 +494,6 @@ where
         self,
         word_docids: Option<grenad::Reader<CursorClonableMmap>>,
         exact_word_docids: Option<grenad::Reader<CursorClonableMmap>>,
-        word_pair_proximity_docids: Option<grenad::Reader<CursorClonableMmap>>,
         word_position_docids: Option<grenad::Reader<CursorClonableMmap>>,
         word_fid_docids: Option<grenad::Reader<CursorClonableMmap>>,
     ) -> Result<()>
@@ -607,32 +614,6 @@ where
             total_databases: TOTAL_POSTING_DATABASE_COUNT,
         });
 
-        if let Some(word_pair_proximity_docids) = word_pair_proximity_docids {
-            // Run the word prefix pair proximity docids update operation.
-            PrefixWordPairsProximityDocids::new(
-                self.wtxn,
-                self.index,
-                self.indexer_config.chunk_compression_type,
-                self.indexer_config.chunk_compression_level,
-            )
-            .execute(
-                word_pair_proximity_docids,
-                &new_prefix_fst_words,
-                &common_prefix_fst_words,
-                &del_prefix_fst_words,
-            )?;
-        }
-
-        if (self.should_abort)() {
-            return Err(Error::InternalError(InternalError::AbortedIndexation));
-        }
-
-        databases_seen += 1;
-        (self.progress)(UpdateIndexingStep::MergeDataIntoFinalDatabase {
-            databases_seen,
-            total_databases: TOTAL_POSTING_DATABASE_COUNT,
-        });
-
         if let Some(word_position_docids) = word_position_docids {
             // Run the words prefix position docids update operation.
             let mut builder = WordPrefixIntegerDocids::new(
@@ -690,8 +671,8 @@ where
 fn execute_word_prefix_docids(
     txn: &mut heed::RwTxn,
     reader: grenad::Reader<Cursor<ClonableMmap>>,
-    word_docids_db: Database<Str, RoaringBitmapCodec>,
+    word_docids_db: Database<Str, CboRoaringBitmapCodec>,
-    word_prefix_docids_db: Database<Str, RoaringBitmapCodec>,
+    word_prefix_docids_db: Database<Str, CboRoaringBitmapCodec>,
     indexer_config: &IndexerConfig,
     new_prefix_fst_words: &[String],
     common_prefix_fst_words: &[&[String]],
@@ -712,14 +693,15 @@ fn execute_word_prefix_docids(
 #[cfg(test)]
 mod tests {
     use big_s::S;
+    use fst::IntoStreamer;
+    use heed::RwTxn;
     use maplit::hashset;
 
     use super::*;
     use crate::documents::documents_batch_reader_from_objects;
     use crate::index::tests::TempIndex;
     use crate::search::TermsMatchingStrategy;
-    use crate::update::DeleteDocuments;
+    use crate::{db_snap, Filter, Search, BEU16};
-    use crate::{db_snap, BEU16};
 
     #[test]
     fn simple_document_replacement() {
@@ -810,11 +792,10 @@ mod tests {
         assert_eq!(count, 1);
 
         // Check that we get only one document from the database.
-        // Since the document has been deleted and re-inserted, its internal docid has been incremented to 1
+        let docs = index.documents(&rtxn, Some(0)).unwrap();
-        let docs = index.documents(&rtxn, Some(1)).unwrap();
         assert_eq!(docs.len(), 1);
         let (id, doc) = docs[0];
-        assert_eq!(id, 1);
+        assert_eq!(id, 0);
 
         // Check that this document is equal to the last one sent.
         let mut doc_iter = doc.iter();
@@ -875,7 +856,7 @@ mod tests {
         assert_eq!(count, 3);
 
         // the document 0 has been deleted and reinserted with the id 3
-        let docs = index.documents(&rtxn, vec![1, 2, 3]).unwrap();
+        let docs = index.documents(&rtxn, vec![1, 2, 0]).unwrap();
         let kevin_position =
             docs.iter().position(|(_, d)| d.get(0).unwrap() == br#""updated kevin""#).unwrap();
         assert_eq!(kevin_position, 2);
@@ -1021,7 +1002,6 @@ mod tests {
         assert_eq!(count, 6);
 
         db_snap!(index, word_docids, "updated");
-        db_snap!(index, soft_deleted_documents_ids, "updated", @"[0, 1, 4, ]");
 
         drop(rtxn);
     }
@@ -1124,17 +1104,15 @@ mod tests {
                 { "objectId": 30,  "title": "Hamlet", "_geo": { "lat": 12, "lng": 89 } }
             ]))
             .unwrap();
-        let mut wtxn = index.write_txn().unwrap();
-        assert_eq!(index.primary_key(&wtxn).unwrap(), Some("objectId"));
 
         // Delete not all of the documents but some of them.
-        let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
+        index.delete_document("30");
-        builder.delete_external_id("30");
-        builder.execute().unwrap();
 
-        let external_documents_ids = index.external_documents_ids(&wtxn).unwrap();
+        let txn = index.read_txn().unwrap();
-        assert!(external_documents_ids.get("30").is_none());
+        assert_eq!(index.primary_key(&txn).unwrap(), Some("objectId"));
-        wtxn.commit().unwrap();
+
+        let external_documents_ids = index.external_documents_ids();
+        assert!(external_documents_ids.get(&txn, "30").unwrap().is_none());
 
         index
             .add_documents(documents!([
@@ -1143,8 +1121,8 @@ mod tests {
             .unwrap();
 
         let wtxn = index.write_txn().unwrap();
-        let external_documents_ids = index.external_documents_ids(&wtxn).unwrap();
+        let external_documents_ids = index.external_documents_ids();
-        assert!(external_documents_ids.get("30").is_some());
+        assert!(external_documents_ids.get(&wtxn, "30").unwrap().is_some());
         wtxn.commit().unwrap();
 
         index
@@ -1438,8 +1416,10 @@ mod tests {
         index.add_documents(documents!({ "a" : { "b" : { "c" :  1 }}})).unwrap();
 
         let rtxn = index.read_txn().unwrap();
-        let external_documents_ids = index.external_documents_ids(&rtxn).unwrap();
+        let all_documents_count = index.all_documents(&rtxn).unwrap().count();
-        assert!(external_documents_ids.get("1").is_some());
+        assert_eq!(all_documents_count, 1);
+        let external_documents_ids = index.external_documents_ids();
+        assert!(external_documents_ids.get(&rtxn, "1").unwrap().is_some());
     }
 
     #[test]
@@ -1493,12 +1473,6 @@ mod tests {
         3   2    second       second
         3   3    third        third
         "###);
-        db_snap!(index, string_faceted_documents_ids, @r###"
-        0   []
-        1   []
-        2   []
-        3   [0, 1, 2, 3, ]
-        "###);
 
         let rtxn = index.read_txn().unwrap();
 
@@ -1522,12 +1496,6 @@ mod tests {
 
         db_snap!(index, facet_id_string_docids, @"");
         db_snap!(index, field_id_docid_facet_strings, @"");
-        db_snap!(index, string_faceted_documents_ids, @r###"
-        0   []
-        1   []
-        2   []
-        3   [0, 1, 2, 3, ]
-        "###);
 
         let rtxn = index.read_txn().unwrap();
 
@@ -1554,12 +1522,6 @@ mod tests {
         3   2    second       second
         3   3    third        third
         "###);
-        db_snap!(index, string_faceted_documents_ids, @r###"
-        0   []
-        1   []
-        2   []
-        3   [0, 1, 2, 3, ]
-        "###);
 
         let rtxn = index.read_txn().unwrap();
 
@@ -1722,7 +1684,7 @@ mod tests {
 
         let wtxn = index.read_txn().unwrap();
 
-        let map = index.external_documents_ids(&wtxn).unwrap().to_hash_map();
+        let map = index.external_documents_ids().to_hash_map(&wtxn).unwrap();
         let ids = map.values().collect::<HashSet<_>>();
 
         assert_eq!(ids.len(), map.len());
@@ -2534,17 +2496,8 @@ mod tests {
         db_snap!(index, word_fid_docids, 2, @"a48d3f88db33f94bc23110a673ea49e4");
         db_snap!(index, word_position_docids, 2, @"3c9e66c6768ae2cf42b46b2c46e46a83");
 
-        let mut wtxn = index.write_txn().unwrap();
-
         // Delete not all of the documents but some of them.
-        let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
+        index.delete_documents(vec!["0".into(), "3".into()]);
-        builder.strategy(DeletionStrategy::AlwaysHard);
-        builder.delete_external_id("0");
-        builder.delete_external_id("3");
-        let result = builder.execute().unwrap();
-        println!("{result:?}");
-
-        wtxn.commit().unwrap();
 
         db_snap!(index, word_fid_docids, 3, @"4c2e2a1832e5802796edc1638136d933");
         db_snap!(index, word_position_docids, 3, @"74f556b91d161d997a89468b4da1cb8f");
@@ -2599,8 +2552,7 @@ mod tests {
             ),
         ]
         */
-        let mut index = TempIndex::new();
+        let index = TempIndex::new();
-        index.index_documents_config.deletion_strategy = DeletionStrategy::AlwaysHard;
 
         // START OF BATCH
 
@@ -2640,8 +2592,7 @@ mod tests {
         {"id":1,"doggo":"bernese"}
         "###);
         db_snap!(index, external_documents_ids, @r###"
-        soft:
+        docids:
-        hard:
         1                        0
         "###);
 
@@ -2686,13 +2637,10 @@ mod tests {
         "###);
 
         db_snap!(index, external_documents_ids, @r###"
-        soft:
+        docids:
-        hard:
         0                        1
         "###);
 
-        db_snap!(index, soft_deleted_documents_ids, @"[]");
-
         // BATCH 3
 
         println!("--- ENTERING BATCH 3");
@@ -2734,4 +2682,537 @@ mod tests {
         let res = index.search(&rtxn).execute().unwrap();
         index.documents(&rtxn, res.documents_ids).unwrap();
     }
+
+    fn delete_documents<'t>(
+        wtxn: &mut RwTxn<'t, '_>,
+        index: &'t TempIndex,
+        external_ids: &[&str],
+    ) -> Vec<u32> {
+        let external_document_ids = index.external_documents_ids();
+        let ids_to_delete: Vec<u32> = external_ids
+            .iter()
+            .map(|id| external_document_ids.get(wtxn, id).unwrap().unwrap())
+            .collect();
+
+        // Delete some documents.
+        index.delete_documents_using_wtxn(
+            wtxn,
+            external_ids.iter().map(ToString::to_string).collect(),
+        );
+
+        ids_to_delete
+    }
+
+    #[test]
+    fn delete_documents_with_numbers_as_primary_key() {
+        let index = TempIndex::new();
+
+        let mut wtxn = index.write_txn().unwrap();
+        index
+            .add_documents_using_wtxn(
+                &mut wtxn,
+                documents!([
+                    { "id": 0, "name": "kevin", "object": { "key1": "value1", "key2": "value2" } },
+                    { "id": 1, "name": "kevina", "array": ["I", "am", "fine"] },
+                    { "id": 2, "name": "benoit", "array_of_object": [{ "wow": "amazing" }] }
+                ]),
+            )
+            .unwrap();
+
+        // delete those documents, ids are synchronous therefore 0, 1, and 2.
+        index.delete_documents_using_wtxn(&mut wtxn, vec![S("0"), S("1"), S("2")]);
+
+        wtxn.commit().unwrap();
+
+        // All these snapshots should be empty since the database was cleared
+        db_snap!(index, documents_ids);
+        db_snap!(index, word_docids);
+        db_snap!(index, word_pair_proximity_docids);
+        db_snap!(index, facet_id_exists_docids);
+
+        let rtxn = index.read_txn().unwrap();
+
+        assert!(index.field_distribution(&rtxn).unwrap().is_empty());
+    }
+
+    #[test]
+    fn delete_documents_with_strange_primary_key() {
+        let index = TempIndex::new();
+
+        index
+            .update_settings(|settings| settings.set_searchable_fields(vec!["name".to_string()]))
+            .unwrap();
+
+        let mut wtxn = index.write_txn().unwrap();
+        index
+            .add_documents_using_wtxn(
+                &mut wtxn,
+                documents!([
+                    { "mysuperid": 0, "name": "kevin" },
+                    { "mysuperid": 1, "name": "kevina" },
+                    { "mysuperid": 2, "name": "benoit" }
+                ]),
+            )
+            .unwrap();
+        wtxn.commit().unwrap();
+
+        let mut wtxn = index.write_txn().unwrap();
+
+        // Delete not all of the documents but some of them.
+        index.delete_documents_using_wtxn(&mut wtxn, vec![S("0"), S("1")]);
+
+        wtxn.commit().unwrap();
+
+        db_snap!(index, documents_ids);
+        db_snap!(index, word_docids);
+        db_snap!(index, word_pair_proximity_docids);
+    }
+
+    #[test]
+    fn filtered_placeholder_search_should_not_return_deleted_documents() {
+        let index = TempIndex::new();
+
+        let mut wtxn = index.write_txn().unwrap();
+
+        index
+            .update_settings_using_wtxn(&mut wtxn, |settings| {
+                settings.set_primary_key(S("docid"));
+                settings.set_filterable_fields(hashset! { S("label"), S("label2") });
+            })
+            .unwrap();
+
+        index
+            .add_documents_using_wtxn(
+                &mut wtxn,
+                documents!([
+                    { "docid": "1_4",  "label": ["sign"] },
+                    { "docid": "1_5",  "label": ["letter"] },
+                    { "docid": "1_7",  "label": ["abstract","cartoon","design","pattern"] },
+                    { "docid": "1_36", "label": ["drawing","painting","pattern"] },
+                    { "docid": "1_37", "label": ["art","drawing","outdoor"] },
+                    { "docid": "1_38", "label": ["aquarium","art","drawing"] },
+                    { "docid": "1_39", "label": ["abstract"] },
+                    { "docid": "1_40", "label": ["cartoon"] },
+                    { "docid": "1_41", "label": ["art","drawing"] },
+                    { "docid": "1_42", "label": ["art","pattern"] },
+                    { "docid": "1_43", "label": ["abstract","art","drawing","pattern"] },
+                    { "docid": "1_44", "label": ["drawing"] },
+                    { "docid": "1_45", "label": ["art"] },
+                    { "docid": "1_46", "label": ["abstract","colorfulness","pattern"] },
+                    { "docid": "1_47", "label": ["abstract","pattern"] },
+                    { "docid": "1_52", "label": ["abstract","cartoon"] },
+                    { "docid": "1_57", "label": ["abstract","drawing","pattern"] },
+                    { "docid": "1_58", "label": ["abstract","art","cartoon"] },
+                    { "docid": "1_68", "label": ["design"] },
+                    { "docid": "1_69", "label": ["geometry"] },
+                    { "docid": "1_70", "label2": ["geometry", 1.2] },
+                    { "docid": "1_71", "label2": ["design", 2.2] },
+                    { "docid": "1_72", "label2": ["geometry", 1.2] }
+                ]),
+            )
+            .unwrap();
+
+        delete_documents(&mut wtxn, &index, &["1_4", "1_70", "1_72"]);
+
+        // Placeholder search with filter
+        let filter = Filter::from_str("label = sign").unwrap().unwrap();
+        let results = index.search(&wtxn).filter(filter).execute().unwrap();
+        assert!(results.documents_ids.is_empty());
+
+        wtxn.commit().unwrap();
+
+        db_snap!(index, word_docids);
+        db_snap!(index, facet_id_f64_docids);
+        db_snap!(index, word_pair_proximity_docids);
+        db_snap!(index, facet_id_exists_docids);
+        db_snap!(index, facet_id_string_docids);
+    }
+
+    #[test]
+    fn placeholder_search_should_not_return_deleted_documents() {
+        let index = TempIndex::new();
+
+        let mut wtxn = index.write_txn().unwrap();
+        index
+            .update_settings_using_wtxn(&mut wtxn, |settings| {
+                settings.set_primary_key(S("docid"));
+            })
+            .unwrap();
+
+        index
+            .add_documents_using_wtxn(
+                &mut wtxn,
+                documents!([
+                    { "docid": "1_4",  "label": ["sign"] },
+                    { "docid": "1_5",  "label": ["letter"] },
+                    { "docid": "1_7",  "label": ["abstract","cartoon","design","pattern"] },
+                    { "docid": "1_36", "label": ["drawing","painting","pattern"] },
+                    { "docid": "1_37", "label": ["art","drawing","outdoor"] },
+                    { "docid": "1_38", "label": ["aquarium","art","drawing"] },
+                    { "docid": "1_39", "label": ["abstract"] },
+                    { "docid": "1_40", "label": ["cartoon"] },
+                    { "docid": "1_41", "label": ["art","drawing"] },
+                    { "docid": "1_42", "label": ["art","pattern"] },
+                    { "docid": "1_43", "label": ["abstract","art","drawing","pattern"] },
+                    { "docid": "1_44", "label": ["drawing"] },
+                    { "docid": "1_45", "label": ["art"] },
+                    { "docid": "1_46", "label": ["abstract","colorfulness","pattern"] },
+                    { "docid": "1_47", "label": ["abstract","pattern"] },
+                    { "docid": "1_52", "label": ["abstract","cartoon"] },
+                    { "docid": "1_57", "label": ["abstract","drawing","pattern"] },
+                    { "docid": "1_58", "label": ["abstract","art","cartoon"] },
+                    { "docid": "1_68", "label": ["design"] },
+                    { "docid": "1_69", "label": ["geometry"] },
+                    { "docid": "1_70", "label2": ["geometry", 1.2] },
+                    { "docid": "1_71", "label2": ["design", 2.2] },
+                    { "docid": "1_72", "label2": ["geometry", 1.2] }
+                ]),
+            )
+            .unwrap();
+
+        let deleted_internal_ids = delete_documents(&mut wtxn, &index, &["1_4"]);
+
+        // Placeholder search
+        let results = index.search(&wtxn).execute().unwrap();
+        assert!(!results.documents_ids.is_empty());
+        for id in results.documents_ids.iter() {
+            assert!(
+                !deleted_internal_ids.contains(id),
+                "The document {} was supposed to be deleted",
+                id
+            );
+        }
+
+        wtxn.commit().unwrap();
+    }
+
+    #[test]
+    fn search_should_not_return_deleted_documents() {
+        let index = TempIndex::new();
+
+        let mut wtxn = index.write_txn().unwrap();
+        index
+            .update_settings_using_wtxn(&mut wtxn, |settings| {
+                settings.set_primary_key(S("docid"));
+            })
+            .unwrap();
+
+        index
+            .add_documents_using_wtxn(
+                &mut wtxn,
+                documents!([
+                    { "docid": "1_4",  "label": ["sign"] },
+                    { "docid": "1_5",  "label": ["letter"] },
+                    { "docid": "1_7",  "label": ["abstract","cartoon","design","pattern"] },
+                    { "docid": "1_36", "label": ["drawing","painting","pattern"] },
+                    { "docid": "1_37", "label": ["art","drawing","outdoor"] },
+                    { "docid": "1_38", "label": ["aquarium","art","drawing"] },
+                    { "docid": "1_39", "label": ["abstract"] },
+                    { "docid": "1_40", "label": ["cartoon"] },
+                    { "docid": "1_41", "label": ["art","drawing"] },
+                    { "docid": "1_42", "label": ["art","pattern"] },
+                    { "docid": "1_43", "label": ["abstract","art","drawing","pattern"] },
+                    { "docid": "1_44", "label": ["drawing"] },
+                    { "docid": "1_45", "label": ["art"] },
+                    { "docid": "1_46", "label": ["abstract","colorfulness","pattern"] },
+                    { "docid": "1_47", "label": ["abstract","pattern"] },
+                    { "docid": "1_52", "label": ["abstract","cartoon"] },
+                    { "docid": "1_57", "label": ["abstract","drawing","pattern"] },
+                    { "docid": "1_58", "label": ["abstract","art","cartoon"] },
+                    { "docid": "1_68", "label": ["design"] },
+                    { "docid": "1_69", "label": ["geometry"] },
+                    { "docid": "1_70", "label2": ["geometry", 1.2] },
+                    { "docid": "1_71", "label2": ["design", 2.2] },
+                    { "docid": "1_72", "label2": ["geometry", 1.2] }
+                ]),
+            )
+            .unwrap();
+
+        let deleted_internal_ids = delete_documents(&mut wtxn, &index, &["1_7", "1_52"]);
+
+        // search for abstract
+        let results = index.search(&wtxn).query("abstract").execute().unwrap();
+        assert!(!results.documents_ids.is_empty());
+        for id in results.documents_ids.iter() {
+            assert!(
+                !deleted_internal_ids.contains(id),
+                "The document {} was supposed to be deleted",
+                id
+            );
+        }
+
+        wtxn.commit().unwrap();
+    }
+
+    #[test]
+    fn geo_filtered_placeholder_search_should_not_return_deleted_documents() {
+        let index = TempIndex::new();
+
+        let mut wtxn = index.write_txn().unwrap();
+        index
+            .update_settings_using_wtxn(&mut wtxn, |settings| {
+                settings.set_primary_key(S("id"));
+                settings.set_filterable_fields(hashset!(S("_geo")));
+                settings.set_sortable_fields(hashset!(S("_geo")));
+            })
+            .unwrap();
+
+        index.add_documents_using_wtxn(&mut wtxn, documents!([
+            { "id": "1",  "city": "Lille",             "_geo": { "lat": 50.6299, "lng": 3.0569 } },
+            { "id": "2",  "city": "Mons-en-Barœul",    "_geo": { "lat": 50.6415, "lng": 3.1106 } },
+            { "id": "3",  "city": "Hellemmes",         "_geo": { "lat": 50.6312, "lng": 3.1106 } },
+            { "id": "4",  "city": "Villeneuve-d'Ascq", "_geo": { "lat": 50.6224, "lng": 3.1476 } },
+            { "id": "5",  "city": "Hem",               "_geo": { "lat": 50.6552, "lng": 3.1897 } },
+            { "id": "6",  "city": "Roubaix",           "_geo": { "lat": 50.6924, "lng": 3.1763 } },
+            { "id": "7",  "city": "Tourcoing",         "_geo": { "lat": 50.7263, "lng": 3.1541 } },
+            { "id": "8",  "city": "Mouscron",          "_geo": { "lat": 50.7453, "lng": 3.2206 } },
+            { "id": "9",  "city": "Tournai",           "_geo": { "lat": 50.6053, "lng": 3.3758 } },
+            { "id": "10", "city": "Ghent",             "_geo": { "lat": 51.0537, "lng": 3.6957 } },
+            { "id": "11", "city": "Brussels",          "_geo": { "lat": 50.8466, "lng": 4.3370 } },
+            { "id": "12", "city": "Charleroi",         "_geo": { "lat": 50.4095, "lng": 4.4347 } },
+            { "id": "13", "city": "Mons",              "_geo": { "lat": 50.4502, "lng": 3.9623 } },
+            { "id": "14", "city": "Valenciennes",      "_geo": { "lat": 50.3518, "lng": 3.5326 } },
+            { "id": "15", "city": "Arras",             "_geo": { "lat": 50.2844, "lng": 2.7637 } },
+            { "id": "16", "city": "Cambrai",           "_geo": { "lat": 50.1793, "lng": 3.2189 } },
+            { "id": "17", "city": "Bapaume",           "_geo": { "lat": 50.1112, "lng": 2.8547 } },
+            { "id": "18", "city": "Amiens",            "_geo": { "lat": 49.9314, "lng": 2.2710 } },
+            { "id": "19", "city": "Compiègne",         "_geo": { "lat": 49.4449, "lng": 2.7913 } },
+            { "id": "20", "city": "Paris",             "_geo": { "lat": 48.9021, "lng": 2.3708 } }
+        ])).unwrap();
+
+        let external_ids_to_delete = ["5", "6", "7", "12", "17", "19"];
+        let deleted_internal_ids = delete_documents(&mut wtxn, &index, &external_ids_to_delete);
+
+        // Placeholder search with geo filter
+        let filter = Filter::from_str("_geoRadius(50.6924, 3.1763, 20000)").unwrap().unwrap();
+        let results = index.search(&wtxn).filter(filter).execute().unwrap();
+        assert!(!results.documents_ids.is_empty());
+        for id in results.documents_ids.iter() {
+            assert!(
+                !deleted_internal_ids.contains(id),
+                "The document {} was supposed to be deleted",
+                id
+            );
+        }
+
+        wtxn.commit().unwrap();
+
+        db_snap!(index, facet_id_f64_docids);
+        db_snap!(index, facet_id_string_docids);
+    }
+
+    #[test]
+    fn get_documents_should_not_return_deleted_documents() {
+        let index = TempIndex::new();
+
+        let mut wtxn = index.write_txn().unwrap();
+        index
+            .update_settings_using_wtxn(&mut wtxn, |settings| {
+                settings.set_primary_key(S("docid"));
+            })
+            .unwrap();
+
+        index
+            .add_documents_using_wtxn(
+                &mut wtxn,
+                documents!([
+                    { "docid": "1_4",  "label": ["sign"] },
+                    { "docid": "1_5",  "label": ["letter"] },
+                    { "docid": "1_7",  "label": ["abstract","cartoon","design","pattern"] },
+                    { "docid": "1_36", "label": ["drawing","painting","pattern"] },
+                    { "docid": "1_37", "label": ["art","drawing","outdoor"] },
+                    { "docid": "1_38", "label": ["aquarium","art","drawing"] },
+                    { "docid": "1_39", "label": ["abstract"] },
+                    { "docid": "1_40", "label": ["cartoon"] },
+                    { "docid": "1_41", "label": ["art","drawing"] },
+                    { "docid": "1_42", "label": ["art","pattern"] },
+                    { "docid": "1_43", "label": ["abstract","art","drawing","pattern"] },
+                    { "docid": "1_44", "label": ["drawing"] },
+                    { "docid": "1_45", "label": ["art"] },
+                    { "docid": "1_46", "label": ["abstract","colorfulness","pattern"] },
+                    { "docid": "1_47", "label": ["abstract","pattern"] },
+                    { "docid": "1_52", "label": ["abstract","cartoon"] },
+                    { "docid": "1_57", "label": ["abstract","drawing","pattern"] },
+                    { "docid": "1_58", "label": ["abstract","art","cartoon"] },
+                    { "docid": "1_68", "label": ["design"] },
+                    { "docid": "1_69", "label": ["geometry"] },
+                    { "docid": "1_70", "label2": ["geometry", 1.2] },
+                    { "docid": "1_71", "label2": ["design", 2.2] },
+                    { "docid": "1_72", "label2": ["geometry", 1.2] }
+                ]),
+            )
+            .unwrap();
+
+        let deleted_external_ids = ["1_7", "1_52"];
+        let deleted_internal_ids = delete_documents(&mut wtxn, &index, &deleted_external_ids);
+
+        // list all documents
+        let results = index.all_documents(&wtxn).unwrap();
+        for result in results {
+            let (id, _) = result.unwrap();
+            assert!(
+                !deleted_internal_ids.contains(&id),
+                "The document {} was supposed to be deleted",
+                id
+            );
+        }
+
+        // list internal document ids
+        let results = index.documents_ids(&wtxn).unwrap();
+        for id in results {
+            assert!(
+                !deleted_internal_ids.contains(&id),
+                "The document {} was supposed to be deleted",
+                id
+            );
+        }
+        wtxn.commit().unwrap();
+
+        let rtxn = index.read_txn().unwrap();
+
+        // get internal docids from deleted external document ids
+        let results = index.external_documents_ids();
+        for id in deleted_external_ids {
+            assert!(
+                results.get(&rtxn, id).unwrap().is_none(),
+                "The document {} was supposed to be deleted",
+                id
+            );
+        }
+        drop(rtxn);
+    }
+
+    #[test]
+    fn stats_should_not_return_deleted_documents() {
+        let index = TempIndex::new();
+
+        let mut wtxn = index.write_txn().unwrap();
+
+        index
+            .update_settings_using_wtxn(&mut wtxn, |settings| {
+                settings.set_primary_key(S("docid"));
+            })
+            .unwrap();
+
+        index.add_documents_using_wtxn(&mut wtxn, documents!([
+            { "docid": "1_4",  "label": ["sign"]},
+            { "docid": "1_5",  "label": ["letter"]},
+            { "docid": "1_7",  "label": ["abstract","cartoon","design","pattern"], "title": "Mickey Mouse"},
+            { "docid": "1_36", "label": ["drawing","painting","pattern"]},
+            { "docid": "1_37", "label": ["art","drawing","outdoor"]},
+            { "docid": "1_38", "label": ["aquarium","art","drawing"], "title": "Nemo"},
+            { "docid": "1_39", "label": ["abstract"]},
+            { "docid": "1_40", "label": ["cartoon"]},
+            { "docid": "1_41", "label": ["art","drawing"]},
+            { "docid": "1_42", "label": ["art","pattern"]},
+            { "docid": "1_43", "label": ["abstract","art","drawing","pattern"], "number": 32i32},
+            { "docid": "1_44", "label": ["drawing"], "number": 44i32},
+            { "docid": "1_45", "label": ["art"]},
+            { "docid": "1_46", "label": ["abstract","colorfulness","pattern"]},
+            { "docid": "1_47", "label": ["abstract","pattern"]},
+            { "docid": "1_52", "label": ["abstract","cartoon"]},
+            { "docid": "1_57", "label": ["abstract","drawing","pattern"]},
+            { "docid": "1_58", "label": ["abstract","art","cartoon"]},
+            { "docid": "1_68", "label": ["design"]},
+            { "docid": "1_69", "label": ["geometry"]}
+        ])).unwrap();
+
+        delete_documents(&mut wtxn, &index, &["1_7", "1_52"]);
+
+        // count internal documents
+        let results = index.number_of_documents(&wtxn).unwrap();
+        assert_eq!(18, results);
+
+        // count field distribution
+        let results = index.field_distribution(&wtxn).unwrap();
+        assert_eq!(Some(&18), results.get("label"));
+        assert_eq!(Some(&1), results.get("title"));
+        assert_eq!(Some(&2), results.get("number"));
+
+        wtxn.commit().unwrap();
+    }
+
+    #[test]
+    fn stored_detected_script_and_language_should_not_return_deleted_documents() {
+        use charabia::{Language, Script};
+        let index = TempIndex::new();
+        let mut wtxn = index.write_txn().unwrap();
+        index
+            .add_documents_using_wtxn(
+                &mut wtxn,
+                documents!([
+                { "id": "0", "title": "The quick (\"brown\") fox can't jump 32.3 feet, right? Brr, it's 29.3°F!" },
+                { "id": "1", "title": "人人生而自由﹐在尊嚴和權利上一律平等。他們賦有理性和良心﹐並應以兄弟關係的精神互相對待。" },
+                { "id": "2", "title": "הַשּׁוּעָל הַמָּהִיר (״הַחוּם״) לֹא יָכוֹל לִקְפֹּץ 9.94 מֶטְרִים, נָכוֹן? ברר, 1.5°C- בַּחוּץ!" },
+                { "id": "3", "title": "関西国際空港限定トートバッグ すもももももももものうち" },
+                { "id": "4", "title": "ภาษาไทยง่ายนิดเดียว" },
+                { "id": "5", "title": "The quick 在尊嚴和權利上一律平等。" },
+            ]))
+            .unwrap();
+
+        let key_cmn = (Script::Cj, Language::Cmn);
+        let cj_cmn_docs =
+            index.script_language_documents_ids(&wtxn, &key_cmn).unwrap().unwrap_or_default();
+        let mut expected_cj_cmn_docids = RoaringBitmap::new();
+        expected_cj_cmn_docids.push(1);
+        expected_cj_cmn_docids.push(5);
+        assert_eq!(cj_cmn_docs, expected_cj_cmn_docids);
+
+        delete_documents(&mut wtxn, &index, &["1"]);
+        wtxn.commit().unwrap();
+
+        let rtxn = index.read_txn().unwrap();
+        let cj_cmn_docs =
+            index.script_language_documents_ids(&rtxn, &key_cmn).unwrap().unwrap_or_default();
+        let mut expected_cj_cmn_docids = RoaringBitmap::new();
+        expected_cj_cmn_docids.push(5);
+        assert_eq!(cj_cmn_docs, expected_cj_cmn_docids);
+    }
+
+    #[test]
+    fn delete_words_exact_attributes() {
+        let index = TempIndex::new();
+
+        index
+            .update_settings(|settings| {
+                settings.set_primary_key(S("id"));
+                settings.set_searchable_fields(vec![S("text"), S("exact")]);
+                settings.set_exact_attributes(vec![S("exact")].into_iter().collect());
+            })
+            .unwrap();
+
+        index
+            .add_documents(documents!([
+                { "id": 0, "text": "hello" },
+                { "id": 1, "exact": "hello"}
+            ]))
+            .unwrap();
+        db_snap!(index, word_docids, 1, @r###"
+        hello            [0, ]
+        "###);
+        db_snap!(index, exact_word_docids, 1, @r###"
+        hello            [1, ]
+        "###);
+        db_snap!(index, words_fst, 1, @"300000000000000001084cfcfc2ce1000000016000000090ea47f");
+
+        let mut wtxn = index.write_txn().unwrap();
+        let deleted_internal_ids = delete_documents(&mut wtxn, &index, &["1"]);
+        wtxn.commit().unwrap();
+
+        db_snap!(index, word_docids, 2, @r###"
+        hello            [0, ]
+        "###);
+        db_snap!(index, exact_word_docids, 2, @"");
+        db_snap!(index, words_fst, 2, @"300000000000000001084cfcfc2ce1000000016000000090ea47f");
+
+        insta::assert_snapshot!(format!("{deleted_internal_ids:?}"), @"[1]");
+        let txn = index.read_txn().unwrap();
+        let words = index.words_fst(&txn).unwrap().into_stream().into_strs().unwrap();
+        insta::assert_snapshot!(format!("{words:?}"), @r###"["hello"]"###);
+
+        let mut s = Search::new(&txn, &index);
+        s.query("hello");
+        let crate::SearchResult { documents_ids, .. } = s.execute().unwrap();
+        insta::assert_snapshot!(format!("{documents_ids:?}"), @"[0]");
+    }
 }

milli/src/update/index_documents/snapshots/mod.rs/delete_documents_with_numbers_as_primary_key/documents_ids.snap

@@ -0,0 +1,4 @@
+---
+source: milli/src/update/index_documents/mod.rs
+---
+[]

milli/src/update/index_documents/snapshots/mod.rs/delete_documents_with_numbers_as_primary_key/facet_id_exists_docids.snap

@@ -0,0 +1,4 @@
+---
+source: milli/src/update/index_documents/mod.rs
+---
+

milli/src/update/index_documents/snapshots/mod.rs/delete_documents_with_numbers_as_primary_key/word_docids.snap

@@ -0,0 +1,4 @@
+---
+source: milli/src/update/index_documents/mod.rs
+---
+

milli/src/update/index_documents/snapshots/mod.rs/delete_documents_with_numbers_as_primary_key/word_pair_proximity_docids.snap

@@ -0,0 +1,4 @@
+---
+source: milli/src/update/index_documents/mod.rs
+---
+

milli/src/update/index_documents/snapshots/mod.rs/delete_documents_with_strange_primary_key/documents_ids.snap

@@ -0,0 +1,4 @@
+---
+source: milli/src/update/index_documents/mod.rs
+---
+[2, ]

milli/src/update/index_documents/snapshots/mod.rs/delete_documents_with_strange_primary_key/word_docids.snap

@@ -0,0 +1,5 @@
+---
+source: milli/src/update/index_documents/mod.rs
+---
+benoit           [2, ]
+

milli/src/update/index_documents/snapshots/mod.rs/delete_documents_with_strange_primary_key/word_pair_proximity_docids.snap

@@ -0,0 +1,4 @@
+---
+source: milli/src/update/index_documents/mod.rs
+---
+

milli/src/update/index_documents/snapshots/mod.rs/filtered_placeholder_search_should_not_return_deleted_documents/facet_id_exists_docids.snap

@@ -1,5 +1,5 @@
 ---
-source: milli/src/update/delete_documents.rs
+source: milli/src/update/index_documents/mod.rs
 ---
 1   [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, ]
 2   [21, ]

milli/src/update/index_documents/snapshots/mod.rs/filtered_placeholder_search_should_not_return_deleted_documents/facet_id_f64_docids.snap

@@ -0,0 +1,5 @@
+---
+source: milli/src/update/index_documents/mod.rs
+---
+2   0  2.2    1  [21, ]
+

milli/src/update/index_documents/snapshots/mod.rs/filtered_placeholder_search_should_not_return_deleted_documents/facet_id_string_docids.snap

@@ -1,5 +1,5 @@
 ---
-source: milli/src/update/delete_documents.rs
+source: milli/src/update/index_documents/mod.rs
 ---
 1   0  abstract     1  [2, 6, 10, 13, 14, 15, 16, 17, ]
 1   0  aquarium     1  [5, ]

milli/src/update/index_documents/snapshots/mod.rs/filtered_placeholder_search_should_not_return_deleted_documents/word_docids.snap

@@ -1,5 +1,5 @@
 ---
-source: milli/src/update/delete_documents.rs
+source: milli/src/update/index_documents/mod.rs
 ---
 1                [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, ]
 2                [21, ]

milli/src/update/index_documents/snapshots/mod.rs/filtered_placeholder_search_should_not_return_deleted_documents/word_pair_proximity_docids.snap

@@ -1,5 +1,5 @@
 ---
-source: milli/src/update/delete_documents.rs
+source: milli/src/update/index_documents/mod.rs
 ---
 1  1                36               [3, ]
 1  1                37               [4, ]

milli/src/update/index_documents/snapshots/mod.rs/geo_filtered_placeholder_search_should_not_return_deleted_documents/facet_id_f64_docids.snap

@@ -1,5 +1,5 @@
 ---
-source: milli/src/update/delete_documents.rs
+source: milli/src/update/index_documents/mod.rs
 ---
 3   0  48.9021 1  [19, ]
 3   0  49.9314 1  [17, ]

milli/src/update/index_documents/snapshots/mod.rs/geo_filtered_placeholder_search_should_not_return_deleted_documents/facet_id_string_docids.snap

@@ -0,0 +1,4 @@
+---
+source: milli/src/update/index_documents/mod.rs
+---
+

milli/src/update/index_documents/snapshots/mod.rs/simple_documents_replace/updated/word_docids.snap

@@ -1,60 +1,56 @@
 ---
 source: milli/src/update/index_documents/mod.rs
 ---
-0                [1, 7, ]
+0                [1, ]
 1                [2, ]
-10               [1, 7, ]
+10               [1, ]
-12               [0, 8, ]
+12               [0, ]
 1344             [3, ]
-1813             [8, ]
+1813             [0, ]
-2                [0, 8, ]
+2                [0, ]
 23               [5, ]
 25               [2, ]
-3                [0, 8, ]
+3                [0, ]
 35               [5, ]
-4                [4, 6, ]
+4                [4, ]
-42               [0, 5, 8, ]
+42               [0, 5, ]
-456              [1, 7, ]
+456              [1, ]
-5                [0, 8, ]
+5                [0, ]
 99               [2, ]
 adams            [5, ]
-adventure        [1, 7, ]
+adventure        [1, ]
 alice            [2, ]
-and              [0, 4, 6, 8, ]
+and              [0, 4, ]
-antoine          [1, 7, ]
+antoine          [1, ]
-austen           [8, ]
+austen           [0, ]
-austin           [0, ]
+blood            [4, ]
-blood            [4, 6, ]
 carroll          [2, ]
-de               [1, 7, ]
+de               [1, ]
 douglas          [5, ]
-exupery          [1, 7, ]
+exupery          [1, ]
-fantasy          [2, 3, 4, 6, ]
+fantasy          [2, 3, 4, ]
 galaxy           [5, ]
 guide            [5, ]
-half             [4, 6, ]
+half             [4, ]
-harry            [4, 6, ]
+harry            [4, ]
 hitchhiker       [5, ]
 hobbit           [3, ]
 in               [2, ]
-j                [3, 4, 6, 8, ]
+j                [0, 3, 4, ]
-jane             [0, ]
+k                [4, ]
-k                [4, 6, ]
-le               [1, ]
 lewis            [2, ]
-little           [7, ]
+little           [1, ]
-petit            [1, ]
+potter           [4, ]
-potter           [4, 6, ]
+prejudice        [0, ]
-prejudice        [0, 8, ]
+pride            [0, ]
-pride            [0, 8, ]
+prince           [1, ]
-prince           [1, 4, 7, ]
+princess         [4, ]
-princess         [6, ]
 r                [3, ]
-romance          [0, 8, ]
+romance          [0, ]
-rowling          [4, 6, ]
+rowling          [4, ]
 s                [5, ]
-saint            [1, 7, ]
+saint            [1, ]
-the              [3, 4, 5, 6, 7, ]
+the              [1, 3, 4, 5, ]
 to               [5, ]
 tolkien          [3, ]
 wonderland       [2, ]

milli/src/update/index_documents/transform.rs

@@ -1,5 +1,6 @@
 use std::borrow::Cow;
-use std::collections::hash_map::Entry;
+use std::collections::btree_map::Entry as BEntry;
+use std::collections::hash_map::Entry as HEntry;
 use std::collections::{HashMap, HashSet};
 use std::fs::File;
 use std::io::{Read, Seek};
@@ -7,18 +8,21 @@ use std::io::{Read, Seek};
 use fxhash::FxHashMap;
 use heed::RoTxn;
 use itertools::Itertools;
-use obkv::{KvReader, KvWriter};
+use obkv::{KvReader, KvReaderU16, KvWriter};
 use roaring::RoaringBitmap;
 use serde_json::Value;
 use smartstring::SmartString;
 
 use super::helpers::{
-    create_sorter, create_writer, keep_latest_obkv, merge_obkvs_and_operations, MergeFn,
+    create_sorter, create_writer, keep_first, obkvs_keep_last_addition_merge_deletions,
+    obkvs_merge_additions_and_deletions, sorter_into_reader, MergeFn,
 };
 use super::{IndexDocumentsMethod, IndexerConfig};
 use crate::documents::{DocumentsBatchIndex, EnrichedDocument, EnrichedDocumentsBatchReader};
 use crate::error::{Error, InternalError, UserError};
 use crate::index::{db_name, main_key};
+use crate::update::del_add::{into_del_add_obkv, DelAdd, DelAddOperation, KvReaderDelAdd};
+use crate::update::index_documents::GrenadParameters;
 use crate::update::{AvailableDocumentsIds, ClearDocuments, UpdateIndexingStep};
 use crate::{
     FieldDistribution, FieldId, FieldIdMapMissingEntry, FieldsIdsMap, Index, Result, BEU32,
@@ -28,9 +32,6 @@ pub struct TransformOutput {
     pub primary_key: String,
     pub fields_ids_map: FieldsIdsMap,
     pub field_distribution: FieldDistribution,
-    pub new_external_documents_ids: fst::Map<Cow<'static, [u8]>>,
-    pub new_documents_ids: RoaringBitmap,
-    pub replaced_documents_ids: RoaringBitmap,
     pub documents_count: usize,
     pub original_documents: File,
     pub flattened_documents: File,
@@ -106,8 +107,8 @@ impl<'a, 'i> Transform<'a, 'i> {
         // We must choose the appropriate merge function for when two or more documents
         // with the same user id must be merged or fully replaced in the same batch.
         let merge_function = match index_documents_method {
-            IndexDocumentsMethod::ReplaceDocuments => keep_latest_obkv,
+            IndexDocumentsMethod::ReplaceDocuments => obkvs_keep_last_addition_merge_deletions,
-            IndexDocumentsMethod::UpdateDocuments => merge_obkvs_and_operations,
+            IndexDocumentsMethod::UpdateDocuments => obkvs_merge_additions_and_deletions,
         };
 
         // We initialize the sorter with the user indexing settings.
@@ -130,17 +131,13 @@ impl<'a, 'i> Transform<'a, 'i> {
             indexer_settings.max_memory.map(|mem| mem / 2),
         );
         let documents_ids = index.documents_ids(wtxn)?;
-        let soft_deleted_documents_ids = index.soft_deleted_documents_ids(wtxn)?;
 
         Ok(Transform {
             index,
             fields_ids_map: index.fields_ids_map(wtxn)?,
             indexer_settings,
             autogenerate_docids,
-            available_documents_ids: AvailableDocumentsIds::from_documents_ids(
+            available_documents_ids: AvailableDocumentsIds::from_documents_ids(&documents_ids),
-                &documents_ids,
-                &soft_deleted_documents_ids,
-            ),
             original_sorter,
             flattened_sorter,
             index_documents_method,
@@ -151,6 +148,7 @@ impl<'a, 'i> Transform<'a, 'i> {
         })
     }
 
+    #[logging_timer::time]
     pub fn read_documents<R, FP, FA>(
         &mut self,
         reader: EnrichedDocumentsBatchReader<R>,
@@ -163,8 +161,10 @@ impl<'a, 'i> Transform<'a, 'i> {
         FP: Fn(UpdateIndexingStep) + Sync,
         FA: Fn() -> bool + Sync,
     {
+        puffin::profile_function!();
+
         let (mut cursor, fields_index) = reader.into_cursor_and_fields_index();
-        let external_documents_ids = self.index.external_documents_ids(wtxn)?;
+        let external_documents_ids = self.index.external_documents_ids();
         let mapping = create_fields_mapping(&mut self.fields_ids_map, &fields_index)?;
 
         let primary_key = cursor.primary_key().to_string();
@@ -172,7 +172,8 @@ impl<'a, 'i> Transform<'a, 'i> {
             self.fields_ids_map.insert(&primary_key).ok_or(UserError::AttributeLimitReached)?;
 
         let mut obkv_buffer = Vec::new();
-        let mut document_sorter_buffer = Vec::new();
+        let mut document_sorter_value_buffer = Vec::new();
+        let mut document_sorter_key_buffer = Vec::new();
         let mut documents_count = 0;
         let mut docid_buffer: Vec<u8> = Vec::new();
         let mut field_buffer: Vec<(u16, Cow<[u8]>)> = Vec::new();
@@ -213,29 +214,30 @@ impl<'a, 'i> Transform<'a, 'i> {
             field_buffer_cache.sort_unstable_by(|(f1, _), (f2, _)| f1.cmp(f2));
 
             // Build the new obkv document.
-            let mut writer = obkv::KvWriter::new(&mut obkv_buffer);
+            let mut writer = KvWriter::new(&mut obkv_buffer);
             for (k, v) in field_buffer_cache.iter() {
                 writer.insert(*k, v)?;
             }
 
             let mut original_docid = None;
-
             let docid = match self.new_external_documents_ids_builder.entry((*external_id).into()) {
-                Entry::Occupied(entry) => *entry.get() as u32,
+                HEntry::Occupied(entry) => *entry.get() as u32,
-                Entry::Vacant(entry) => {
+                HEntry::Vacant(entry) => {
-                    // If the document was already in the db we mark it as a replaced document.
+                    let docid = match external_documents_ids.get(wtxn, entry.key())? {
-                    // It'll be deleted later.
+                        Some(docid) => {
-                    if let Some(docid) = external_documents_ids.get(entry.key()) {
+                            // If it was already in the list of replaced documents it means it was deleted
-                        // If it was already in the list of replaced documents it means it was deleted
+                            // by the remove_document method. We should starts as if it never existed.
-                        // by the remove_document method. We should starts as if it never existed.
+                            if self.replaced_documents_ids.insert(docid) {
-                        if self.replaced_documents_ids.insert(docid) {
+                                original_docid = Some(docid);
-                            original_docid = Some(docid);
+                            }
+
+                            docid
                         }
-                    }
+                        None => self
-                    let docid = self
+                            .available_documents_ids
-                        .available_documents_ids
+                            .next()
-                        .next()
+                            .ok_or(UserError::DocumentLimitReached)?,
-                        .ok_or(UserError::DocumentLimitReached)?;
+                    };
                     entry.insert(docid as u64);
                     docid
                 }
@@ -263,47 +265,68 @@ impl<'a, 'i> Transform<'a, 'i> {
                     skip_insertion = true;
                 } else {
                     // we associate the base document with the new key, everything will get merged later.
-                    document_sorter_buffer.clear();
+                    let deladd_operation = match self.index_documents_method {
-                    document_sorter_buffer.push(Operation::Addition as u8);
+                        IndexDocumentsMethod::UpdateDocuments => {
-                    document_sorter_buffer.extend_from_slice(base_obkv);
+                            DelAddOperation::DeletionAndAddition
-                    self.original_sorter.insert(docid.to_be_bytes(), &document_sorter_buffer)?;
-                    match self.flatten_from_fields_ids_map(KvReader::new(base_obkv))? {
-                        Some(flattened_obkv) => {
-                            // we recreate our buffer with the flattened documents
-                            document_sorter_buffer.clear();
-                            document_sorter_buffer.push(Operation::Addition as u8);
-                            document_sorter_buffer.extend_from_slice(&flattened_obkv);
-                            self.flattened_sorter
-                                .insert(docid.to_be_bytes(), &document_sorter_buffer)?
                         }
-                        None => self
+                        IndexDocumentsMethod::ReplaceDocuments => DelAddOperation::Deletion,
-                            .flattened_sorter
+                    };
-                            .insert(docid.to_be_bytes(), &document_sorter_buffer)?,
+                    document_sorter_key_buffer.clear();
+                    document_sorter_key_buffer.extend_from_slice(&docid.to_be_bytes());
+                    document_sorter_key_buffer.extend_from_slice(external_id.as_bytes());
+                    document_sorter_value_buffer.clear();
+                    document_sorter_value_buffer.push(Operation::Addition as u8);
+                    into_del_add_obkv(
+                        KvReaderU16::new(base_obkv),
+                        deladd_operation,
+                        &mut document_sorter_value_buffer,
+                    )?;
+                    self.original_sorter
+                        .insert(&document_sorter_key_buffer, &document_sorter_value_buffer)?;
+                    let base_obkv = KvReader::new(base_obkv);
+                    if let Some(flattened_obkv) = self.flatten_from_fields_ids_map(base_obkv)? {
+                        // we recreate our buffer with the flattened documents
+                        document_sorter_value_buffer.clear();
+                        document_sorter_value_buffer.push(Operation::Addition as u8);
+                        into_del_add_obkv(
+                            KvReaderU16::new(&flattened_obkv),
+                            deladd_operation,
+                            &mut document_sorter_value_buffer,
+                        )?;
                     }
+                    self.flattened_sorter
+                        .insert(docid.to_be_bytes(), &document_sorter_value_buffer)?;
                 }
             }
 
             if !skip_insertion {
                 self.new_documents_ids.insert(docid);
 
-                document_sorter_buffer.clear();
+                document_sorter_key_buffer.clear();
-                document_sorter_buffer.push(Operation::Addition as u8);
+                document_sorter_key_buffer.extend_from_slice(&docid.to_be_bytes());
-                document_sorter_buffer.extend_from_slice(&obkv_buffer);
+                document_sorter_key_buffer.extend_from_slice(external_id.as_bytes());
+                document_sorter_value_buffer.clear();
+                document_sorter_value_buffer.push(Operation::Addition as u8);
+                into_del_add_obkv(
+                    KvReaderU16::new(&obkv_buffer),
+                    DelAddOperation::Addition,
+                    &mut document_sorter_value_buffer,
+                )?;
                 // We use the extracted/generated user id as the key for this document.
-                self.original_sorter.insert(docid.to_be_bytes(), &document_sorter_buffer)?;
+                self.original_sorter
+                    .insert(&document_sorter_key_buffer, &document_sorter_value_buffer)?;
 
-                match self.flatten_from_fields_ids_map(KvReader::new(&obkv_buffer))? {
+                let flattened_obkv = KvReader::new(&obkv_buffer);
-                    Some(flattened_obkv) => {
+                if let Some(obkv) = self.flatten_from_fields_ids_map(flattened_obkv)? {
-                        document_sorter_buffer.clear();
+                    document_sorter_value_buffer.clear();
-                        document_sorter_buffer.push(Operation::Addition as u8);
+                    document_sorter_value_buffer.push(Operation::Addition as u8);
-                        document_sorter_buffer.extend_from_slice(&flattened_obkv);
+                    into_del_add_obkv(
-                        self.flattened_sorter
+                        KvReaderU16::new(&obkv),
-                            .insert(docid.to_be_bytes(), &document_sorter_buffer)?
+                        DelAddOperation::Addition,
-                    }
+                        &mut document_sorter_value_buffer,
-                    None => self
+                    )?
-                        .flattened_sorter
-                        .insert(docid.to_be_bytes(), &document_sorter_buffer)?,
                 }
+                self.flattened_sorter.insert(docid.to_be_bytes(), &document_sorter_value_buffer)?;
             }
             documents_count += 1;
 
@@ -338,6 +361,7 @@ impl<'a, 'i> Transform<'a, 'i> {
     /// - If the document to remove was inserted by the `read_documents` method before but was NOT present in the db,
     ///   it's added into the grenad to ensure we don't insert it + removed from the list of new documents ids.
     /// - If the document to remove was not present in either the db or the transform we do nothing.
+    #[logging_timer::time]
     pub fn remove_documents<FA>(
         &mut self,
         mut to_remove: Vec<String>,
@@ -347,54 +371,176 @@ impl<'a, 'i> Transform<'a, 'i> {
     where
         FA: Fn() -> bool + Sync,
     {
+        puffin::profile_function!();
+
         // there may be duplicates in the documents to remove.
         to_remove.sort_unstable();
         to_remove.dedup();
 
-        let external_documents_ids = self.index.external_documents_ids(wtxn)?;
+        let external_documents_ids = self.index.external_documents_ids();
 
         let mut documents_deleted = 0;
+        let mut document_sorter_value_buffer = Vec::new();
+        let mut document_sorter_key_buffer = Vec::new();
         for to_remove in to_remove {
             if should_abort() {
                 return Err(Error::InternalError(InternalError::AbortedIndexation));
             }
 
-            match self.new_external_documents_ids_builder.entry((*to_remove).into()) {
+            // Check if the document has been added in the current indexing process.
-                // if the document was added in a previous iteration of the transform we make it as deleted in the sorters.
+            let deleted_from_current =
-                Entry::Occupied(entry) => {
+                match self.new_external_documents_ids_builder.entry((*to_remove).into()) {
-                    let doc_id = *entry.get() as u32;
+                    // if the document was added in a previous iteration of the transform we make it as deleted in the sorters.
-                    self.original_sorter
+                    HEntry::Occupied(entry) => {
-                        .insert(doc_id.to_be_bytes(), [Operation::Deletion as u8])?;
+                        let docid = *entry.get() as u32;
-                    self.flattened_sorter
+                        // Key is the concatenation of the internal docid and the external one.
-                        .insert(doc_id.to_be_bytes(), [Operation::Deletion as u8])?;
+                        document_sorter_key_buffer.clear();
+                        document_sorter_key_buffer.extend_from_slice(&docid.to_be_bytes());
+                        document_sorter_key_buffer.extend_from_slice(to_remove.as_bytes());
+                        document_sorter_value_buffer.clear();
+                        document_sorter_value_buffer.push(Operation::Deletion as u8);
+                        obkv::KvWriterU16::new(&mut document_sorter_value_buffer).finish().unwrap();
+                        self.original_sorter
+                            .insert(&document_sorter_key_buffer, &document_sorter_value_buffer)?;
+                        self.flattened_sorter
+                            .insert(docid.to_be_bytes(), &document_sorter_value_buffer)?;
 
-                    // we must NOT update the list of replaced_documents_ids
+                        // we must NOT update the list of replaced_documents_ids
-                    // Either:
+                        // Either:
-                    // 1. It's already in it and there is nothing to do
+                        // 1. It's already in it and there is nothing to do
-                    // 2. It wasn't in it because the document was created by a previous batch and since
+                        // 2. It wasn't in it because the document was created by a previous batch and since
-                    //    we're removing it there is nothing to do.
+                        //    we're removing it there is nothing to do.
-                    self.new_documents_ids.remove(doc_id);
+                        self.new_documents_ids.remove(docid);
-                    entry.remove_entry();
+                        entry.remove_entry();
-                }
+                        true
-                Entry::Vacant(entry) => {
-                    // If the document was already in the db we mark it as a `to_delete` document.
-                    // It'll be deleted later. We don't need to push anything to the sorters.
-                    if let Some(docid) = external_documents_ids.get(entry.key()) {
-                        self.replaced_documents_ids.insert(docid);
-                    } else {
-                        // if the document is nowehere to be found, there is nothing to do and we must NOT
-                        // increment the count of documents_deleted
-                        continue;
                     }
+                    HEntry::Vacant(_) => false,
+                };
+
+            // If the document was already in the db we mark it as a `to_delete` document.
+            // Then we push the document in sorters in deletion mode.
+            let deleted_from_db = match external_documents_ids.get(wtxn, &to_remove)? {
+                Some(docid) => {
+                    self.remove_document_from_db(
+                        docid,
+                        to_remove,
+                        wtxn,
+                        &mut document_sorter_key_buffer,
+                        &mut document_sorter_value_buffer,
+                    )?;
+                    true
                 }
+                None => false,
             };
 
+            // increase counter only if the document existed somewhere before.
+            if deleted_from_current || deleted_from_db {
+                documents_deleted += 1;
+            }
+        }
+
+        Ok(documents_deleted)
+    }
+
+    /// Removes documents from db using their internal document ids.
+    ///
+    /// # Warning
+    ///
+    /// This function is dangerous and will only work correctly if:
+    ///
+    /// - All the passed ids currently exist in the database
+    /// - No batching using the standards `remove_documents` and `add_documents` took place
+    ///
+    /// TODO: make it impossible to call `remove_documents` or `add_documents` on an instance that calls this function.
+    #[logging_timer::time]
+    pub fn remove_documents_from_db_no_batch<FA>(
+        &mut self,
+        to_remove: &RoaringBitmap,
+        wtxn: &mut heed::RwTxn,
+        should_abort: FA,
+    ) -> Result<usize>
+    where
+        FA: Fn() -> bool + Sync,
+    {
+        puffin::profile_function!();
+
+        let mut documents_deleted = 0;
+        let mut document_sorter_value_buffer = Vec::new();
+        let mut document_sorter_key_buffer = Vec::new();
+        let external_ids = self.index.external_id_of(wtxn, to_remove.iter())?;
+
+        for (internal_docid, external_docid) in to_remove.iter().zip(external_ids) {
+            let external_docid = external_docid?;
+            if should_abort() {
+                return Err(Error::InternalError(InternalError::AbortedIndexation));
+            }
+            self.remove_document_from_db(
+                internal_docid,
+                external_docid,
+                wtxn,
+                &mut document_sorter_key_buffer,
+                &mut document_sorter_value_buffer,
+            )?;
+
             documents_deleted += 1;
         }
 
         Ok(documents_deleted)
     }
 
+    fn remove_document_from_db(
+        &mut self,
+        internal_docid: u32,
+        external_docid: String,
+        txn: &heed::RoTxn,
+        document_sorter_key_buffer: &mut Vec<u8>,
+        document_sorter_value_buffer: &mut Vec<u8>,
+    ) -> Result<()> {
+        self.replaced_documents_ids.insert(internal_docid);
+
+        // fetch the obkv document
+        let original_key = BEU32::new(internal_docid);
+        let base_obkv = self
+            .index
+            .documents
+            .remap_data_type::<heed::types::ByteSlice>()
+            .get(txn, &original_key)?
+            .ok_or(InternalError::DatabaseMissingEntry {
+                db_name: db_name::DOCUMENTS,
+                key: None,
+            })?;
+
+        // Key is the concatenation of the internal docid and the external one.
+        document_sorter_key_buffer.clear();
+        document_sorter_key_buffer.extend_from_slice(&internal_docid.to_be_bytes());
+        document_sorter_key_buffer.extend_from_slice(external_docid.as_bytes());
+        // push it as to delete in the original_sorter
+        document_sorter_value_buffer.clear();
+        document_sorter_value_buffer.push(Operation::Deletion as u8);
+        into_del_add_obkv(
+            KvReaderU16::new(base_obkv),
+            DelAddOperation::Deletion,
+            document_sorter_value_buffer,
+        )?;
+        self.original_sorter.insert(&document_sorter_key_buffer, &document_sorter_value_buffer)?;
+
+        // flatten it and push it as to delete in the flattened_sorter
+        let flattened_obkv = KvReader::new(base_obkv);
+        if let Some(obkv) = self.flatten_from_fields_ids_map(flattened_obkv)? {
+            // we recreate our buffer with the flattened documents
+            document_sorter_value_buffer.clear();
+            document_sorter_value_buffer.push(Operation::Deletion as u8);
+            into_del_add_obkv(
+                KvReaderU16::new(&obkv),
+                DelAddOperation::Deletion,
+                document_sorter_value_buffer,
+            )?;
+        }
+        self.flattened_sorter
+            .insert(internal_docid.to_be_bytes(), &document_sorter_value_buffer)?;
+        Ok(())
+    }
+
     // Flatten a document from the fields ids map contained in self and insert the new
     // created fields. Returns `None` if the document doesn't need to be flattened.
     fn flatten_from_fields_ids_map(&mut self, obkv: KvReader<FieldId>) -> Result<Option<Vec<u8>>> {
@@ -514,42 +660,10 @@ impl<'a, 'i> Transform<'a, 'i> {
         Ok(())
     }
 
-    fn remove_deleted_documents_from_field_distribution(
-        &self,
-        rtxn: &RoTxn,
-        field_distribution: &mut FieldDistribution,
-    ) -> Result<()> {
-        for deleted_docid in self.replaced_documents_ids.iter() {
-            let obkv = self.index.documents.get(rtxn, &BEU32::new(deleted_docid))?.ok_or(
-                InternalError::DatabaseMissingEntry { db_name: db_name::DOCUMENTS, key: None },
-            )?;
-
-            for (key, _) in obkv.iter() {
-                let name =
-                    self.fields_ids_map.name(key).ok_or(FieldIdMapMissingEntry::FieldId {
-                        field_id: key,
-                        process: "Computing field distribution in transform.",
-                    })?;
-                // We checked that the document was in the db earlier. If we can't find it it means
-                // there is an inconsistency between the field distribution and the field id map.
-                let field =
-                    field_distribution.get_mut(name).ok_or(FieldIdMapMissingEntry::FieldId {
-                        field_id: key,
-                        process: "Accessing field distribution in transform.",
-                    })?;
-                *field -= 1;
-                if *field == 0 {
-                    // since we were able to get the field right before it's safe to unwrap here
-                    field_distribution.remove(name).unwrap();
-                }
-            }
-        }
-        Ok(())
-    }
-
     /// Generate the `TransformOutput` based on the given sorter that can be generated from any
     /// format like CSV, JSON or JSON stream. This sorter must contain a key that is the document
     /// id for the user side and the value must be an obkv where keys are valid fields ids.
+    #[logging_timer::time]
     pub(crate) fn output_from_sorter<F>(
         self,
         wtxn: &mut heed::RwTxn,
@@ -581,17 +695,13 @@ impl<'a, 'i> Transform<'a, 'i> {
         // 2. Add all the new documents to the field distribution
         let mut field_distribution = self.index.field_distribution(wtxn)?;
 
-        self.remove_deleted_documents_from_field_distribution(wtxn, &mut field_distribution)?;
-
         // Here we are going to do the document count + field distribution + `write_into_stream_writer`
         let mut iter = self.original_sorter.into_stream_merger_iter()?;
         // used only for the callback
         let mut documents_count = 0;
 
         while let Some((key, val)) = iter.next()? {
-            if val[0] == Operation::Deletion as u8 {
+            // skip first byte corresponding to the operation type (Deletion or Addition).
-                continue;
-            }
             let val = &val[1..];
 
             // send a callback to show at which step we are
@@ -601,16 +711,51 @@ impl<'a, 'i> Transform<'a, 'i> {
                 total_documents: self.documents_count,
             });
 
-            // We increment all the field of the current document in the field distribution.
+            for (key, value) in KvReader::new(val) {
-            let obkv = KvReader::new(val);
+                let reader = KvReaderDelAdd::new(value);
-
+                match (reader.get(DelAdd::Deletion), reader.get(DelAdd::Addition)) {
-            for (key, _) in obkv.iter() {
+                    (None, None) => {}
-                let name =
+                    (None, Some(_)) => {
-                    self.fields_ids_map.name(key).ok_or(FieldIdMapMissingEntry::FieldId {
+                        // New field
-                        field_id: key,
+                        let name = self.fields_ids_map.name(key).ok_or(
-                        process: "Computing field distribution in transform.",
+                            FieldIdMapMissingEntry::FieldId {
-                    })?;
+                                field_id: key,
-                *field_distribution.entry(name.to_string()).or_insert(0) += 1;
+                                process: "Computing field distribution in transform.",
+                            },
+                        )?;
+                        *field_distribution.entry(name.to_string()).or_insert(0) += 1;
+                    }
+                    (Some(_), None) => {
+                        // Field removed
+                        let name = self.fields_ids_map.name(key).ok_or(
+                            FieldIdMapMissingEntry::FieldId {
+                                field_id: key,
+                                process: "Computing field distribution in transform.",
+                            },
+                        )?;
+                        match field_distribution.entry(name.to_string()) {
+                            BEntry::Vacant(_) => { /* Bug? trying to remove a non-existing field */
+                            }
+                            BEntry::Occupied(mut entry) => {
+                                // attempt to remove one
+                                match entry.get_mut().checked_sub(1) {
+                                    Some(0) => {
+                                        entry.remove();
+                                    }
+                                    Some(new_val) => {
+                                        *entry.get_mut() = new_val;
+                                    }
+                                    None => {
+                                        unreachable!("Attempting to remove a field that wasn't in the field distribution")
+                                    }
+                                }
+                            }
+                        }
+                    }
+                    (Some(_), Some(_)) => {
+                        // Value change, no field distribution change
+                    }
+                }
             }
             writer.insert(key, val)?;
         }
@@ -631,9 +776,7 @@ impl<'a, 'i> Transform<'a, 'i> {
         // We get rids of the `Operation` byte and skip the deleted documents as well.
         let mut iter = self.flattened_sorter.into_stream_merger_iter()?;
         while let Some((key, val)) = iter.next()? {
-            if val[0] == Operation::Deletion as u8 {
+            // skip first byte corresponding to the operation type (Deletion or Addition).
-                continue;
-            }
             let val = &val[1..];
             writer.insert(key, val)?;
         }
@@ -649,15 +792,11 @@ impl<'a, 'i> Transform<'a, 'i> {
         new_external_documents_ids_builder.into_iter().try_for_each(|(key, value)| {
             fst_new_external_documents_ids_builder.insert(key, value)
         })?;
-        let new_external_documents_ids = fst_new_external_documents_ids_builder.into_map();
 
         Ok(TransformOutput {
             primary_key,
             fields_ids_map: self.fields_ids_map,
             field_distribution,
-            new_external_documents_ids: new_external_documents_ids.map_data(Cow::Owned).unwrap(),
-            new_documents_ids: self.new_documents_ids,
-            replaced_documents_ids: self.replaced_documents_ids,
             documents_count: self.documents_count,
             original_documents: original_documents.into_inner().map_err(|err| err.into_error())?,
             flattened_documents: flattened_documents
@@ -687,37 +826,41 @@ impl<'a, 'i> Transform<'a, 'i> {
             .to_string();
         let field_distribution = self.index.field_distribution(wtxn)?;
 
-        // Delete the soft deleted document ids from the maps inside the external_document_ids structure
-        let new_external_documents_ids = {
-            let mut external_documents_ids = self.index.external_documents_ids(wtxn)?;
-            external_documents_ids.delete_soft_deleted_documents_ids_from_fsts()?;
-            // This call should be free and can't fail since the previous method merged both fsts.
-            external_documents_ids.into_static().to_fst()?.into_owned()
-        };
-
         let documents_ids = self.index.documents_ids(wtxn)?;
         let documents_count = documents_ids.len() as usize;
 
-        // We create a final writer to write the new documents in order from the sorter.
+        // We initialize the sorter with the user indexing settings.
-        let mut original_writer = create_writer(
+        let mut original_sorter = create_sorter(
+            grenad::SortAlgorithm::Stable,
+            keep_first,
             self.indexer_settings.chunk_compression_type,
             self.indexer_settings.chunk_compression_level,
-            tempfile::tempfile()?,
+            self.indexer_settings.max_nb_chunks,
+            self.indexer_settings.max_memory.map(|mem| mem / 2),
         );
 
-        // We create a final writer to write the new documents in order from the sorter.
+        // We initialize the sorter with the user indexing settings.
-        let mut flattened_writer = create_writer(
+        let mut flattened_sorter = create_sorter(
+            grenad::SortAlgorithm::Stable,
+            keep_first,
             self.indexer_settings.chunk_compression_type,
             self.indexer_settings.chunk_compression_level,
-            tempfile::tempfile()?,
+            self.indexer_settings.max_nb_chunks,
+            self.indexer_settings.max_memory.map(|mem| mem / 2),
         );
 
         let mut obkv_buffer = Vec::new();
-        for result in self.index.all_documents(wtxn)? {
+        let mut document_sorter_key_buffer = Vec::new();
-            let (docid, obkv) = result?;
+        let mut document_sorter_value_buffer = Vec::new();
+        for result in self.index.external_documents_ids().iter(wtxn)? {
+            let (external_id, docid) = result?;
+            let obkv = self.index.documents.get(wtxn, &docid)?.ok_or(
+                InternalError::DatabaseMissingEntry { db_name: db_name::DOCUMENTS, key: None },
+            )?;
+            let docid = docid.get();
 
             obkv_buffer.clear();
-            let mut obkv_writer = obkv::KvWriter::<_, FieldId>::new(&mut obkv_buffer);
+            let mut obkv_writer = KvWriter::<_, FieldId>::new(&mut obkv_buffer);
 
             // We iterate over the new `FieldsIdsMap` ids in order and construct the new obkv.
             for (id, name) in new_fields_ids_map.iter() {
@@ -727,7 +870,17 @@ impl<'a, 'i> Transform<'a, 'i> {
             }
 
             let buffer = obkv_writer.into_inner()?;
-            original_writer.insert(docid.to_be_bytes(), &buffer)?;
+
+            document_sorter_key_buffer.clear();
+            document_sorter_key_buffer.extend_from_slice(&docid.to_be_bytes());
+            document_sorter_key_buffer.extend_from_slice(external_id.as_bytes());
+            document_sorter_value_buffer.clear();
+            into_del_add_obkv(
+                KvReaderU16::new(buffer),
+                DelAddOperation::Addition,
+                &mut document_sorter_value_buffer,
+            )?;
+            original_sorter.insert(&document_sorter_key_buffer, &document_sorter_value_buffer)?;
 
             // Once we have the document. We're going to flatten it
             // and insert it in the flattened sorter.
@@ -762,29 +915,34 @@ impl<'a, 'i> Transform<'a, 'i> {
                 let value = serde_json::to_vec(&value).map_err(InternalError::SerdeJson)?;
                 writer.insert(fid, &value)?;
             }
-            flattened_writer.insert(docid.to_be_bytes(), &buffer)?;
+            document_sorter_value_buffer.clear();
+            into_del_add_obkv(
+                KvReaderU16::new(&buffer),
+                DelAddOperation::Addition,
+                &mut document_sorter_value_buffer,
+            )?;
+            flattened_sorter.insert(docid.to_be_bytes(), &document_sorter_value_buffer)?;
         }
 
-        // Once we have written all the documents, we extract
+        let grenad_params = GrenadParameters {
-        // the file and reset the seek to be able to read it again.
+            chunk_compression_type: self.indexer_settings.chunk_compression_type,
-        let mut original_documents = original_writer.into_inner()?;
+            chunk_compression_level: self.indexer_settings.chunk_compression_level,
-        original_documents.rewind()?;
+            max_memory: self.indexer_settings.max_memory,
+            max_nb_chunks: self.indexer_settings.max_nb_chunks, // default value, may be chosen.
+        };
 
-        let mut flattened_documents = flattened_writer.into_inner()?;
+        // Once we have written all the documents, we merge everything into a Reader.
-        flattened_documents.rewind()?;
+        let original_documents = sorter_into_reader(original_sorter, grenad_params)?;
+
+        let flattened_documents = sorter_into_reader(flattened_sorter, grenad_params)?;
 
         let output = TransformOutput {
             primary_key,
             fields_ids_map: new_fields_ids_map,
             field_distribution,
-            new_external_documents_ids,
-            new_documents_ids: documents_ids,
-            replaced_documents_ids: RoaringBitmap::default(),
             documents_count,
-            original_documents: original_documents.into_inner().map_err(|err| err.into_error())?,
+            original_documents: original_documents.into_inner().into_inner(),
-            flattened_documents: flattened_documents
+            flattened_documents: flattened_documents.into_inner().into_inner(),
-                .into_inner()
-                .map_err(|err| err.into_error())?,
         };
 
         let new_facets = output.compute_real_facets(wtxn, self.index)?;
@@ -828,38 +986,111 @@ mod test {
 
     #[test]
     fn merge_obkvs() {
-        let mut doc_0 = Vec::new();
+        let mut additive_doc_0 = Vec::new();
-        let mut kv_writer = KvWriter::new(&mut doc_0);
+        let mut deletive_doc_0 = Vec::new();
+        let mut del_add_doc_0 = Vec::new();
+        let mut kv_writer = KvWriter::memory();
         kv_writer.insert(0_u8, [0]).unwrap();
-        kv_writer.finish().unwrap();
+        let buffer = kv_writer.into_inner().unwrap();
-        doc_0.insert(0, Operation::Addition as u8);
+        into_del_add_obkv(
-
+            KvReaderU16::new(&buffer),
-        let ret = merge_obkvs_and_operations(&[], &[Cow::from(doc_0.as_slice())]).unwrap();
+            DelAddOperation::Addition,
-        assert_eq!(*ret, doc_0);
+            &mut additive_doc_0,
-
-        let ret = merge_obkvs_and_operations(
-            &[],
-            &[Cow::from([Operation::Deletion as u8].as_slice()), Cow::from(doc_0.as_slice())],
         )
         .unwrap();
-        assert_eq!(*ret, doc_0);
+        additive_doc_0.insert(0, Operation::Addition as u8);
-
+        into_del_add_obkv(
-        let ret = merge_obkvs_and_operations(
+            KvReaderU16::new(&buffer),
-            &[],
+            DelAddOperation::Deletion,
-            &[Cow::from(doc_0.as_slice()), Cow::from([Operation::Deletion as u8].as_slice())],
+            &mut deletive_doc_0,
         )
         .unwrap();
-        assert_eq!(*ret, [Operation::Deletion as u8]);
+        deletive_doc_0.insert(0, Operation::Deletion as u8);
+        into_del_add_obkv(
+            KvReaderU16::new(&buffer),
+            DelAddOperation::DeletionAndAddition,
+            &mut del_add_doc_0,
+        )
+        .unwrap();
+        del_add_doc_0.insert(0, Operation::Addition as u8);
 
-        let ret = merge_obkvs_and_operations(
+        let mut additive_doc_1 = Vec::new();
+        let mut kv_writer = KvWriter::memory();
+        kv_writer.insert(1_u8, [1]).unwrap();
+        let buffer = kv_writer.into_inner().unwrap();
+        into_del_add_obkv(
+            KvReaderU16::new(&buffer),
+            DelAddOperation::Addition,
+            &mut additive_doc_1,
+        )
+        .unwrap();
+        additive_doc_1.insert(0, Operation::Addition as u8);
+
+        let mut additive_doc_0_1 = Vec::new();
+        let mut kv_writer = KvWriter::memory();
+        kv_writer.insert(0_u8, [0]).unwrap();
+        kv_writer.insert(1_u8, [1]).unwrap();
+        let buffer = kv_writer.into_inner().unwrap();
+        into_del_add_obkv(
+            KvReaderU16::new(&buffer),
+            DelAddOperation::Addition,
+            &mut additive_doc_0_1,
+        )
+        .unwrap();
+        additive_doc_0_1.insert(0, Operation::Addition as u8);
+
+        let ret = obkvs_merge_additions_and_deletions(&[], &[Cow::from(additive_doc_0.as_slice())])
+            .unwrap();
+        assert_eq!(*ret, additive_doc_0);
+
+        let ret = obkvs_merge_additions_and_deletions(
+            &[],
+            &[Cow::from(deletive_doc_0.as_slice()), Cow::from(additive_doc_0.as_slice())],
+        )
+        .unwrap();
+        assert_eq!(*ret, del_add_doc_0);
+
+        let ret = obkvs_merge_additions_and_deletions(
+            &[],
+            &[Cow::from(additive_doc_0.as_slice()), Cow::from(deletive_doc_0.as_slice())],
+        )
+        .unwrap();
+        assert_eq!(*ret, deletive_doc_0);
+
+        let ret = obkvs_merge_additions_and_deletions(
             &[],
             &[
-                Cow::from([Operation::Addition as u8, 1].as_slice()),
+                Cow::from(additive_doc_1.as_slice()),
-                Cow::from([Operation::Deletion as u8].as_slice()),
+                Cow::from(deletive_doc_0.as_slice()),
-                Cow::from(doc_0.as_slice()),
+                Cow::from(additive_doc_0.as_slice()),
             ],
         )
         .unwrap();
-        assert_eq!(*ret, doc_0);
+        assert_eq!(*ret, del_add_doc_0);
+
+        let ret = obkvs_merge_additions_and_deletions(
+            &[],
+            &[Cow::from(additive_doc_1.as_slice()), Cow::from(additive_doc_0.as_slice())],
+        )
+        .unwrap();
+        assert_eq!(*ret, additive_doc_0_1);
+
+        let ret = obkvs_keep_last_addition_merge_deletions(
+            &[],
+            &[Cow::from(additive_doc_1.as_slice()), Cow::from(additive_doc_0.as_slice())],
+        )
+        .unwrap();
+        assert_eq!(*ret, additive_doc_0);
+
+        let ret = obkvs_keep_last_addition_merge_deletions(
+            &[],
+            &[
+                Cow::from(deletive_doc_0.as_slice()),
+                Cow::from(additive_doc_1.as_slice()),
+                Cow::from(additive_doc_0.as_slice()),
+            ],
+        )
+        .unwrap();
+        assert_eq!(*ret, del_add_doc_0);
     }
 }

milli/src/update/index_documents/typed_chunk.rs

@@ -1,5 +1,4 @@
-use std::borrow::Cow;
+use std::collections::{HashMap, HashSet};
-use std::collections::HashMap;
 use std::convert::TryInto;
 use std::fs::File;
 use std::io::{self, BufReader};
@@ -9,32 +8,40 @@ use charabia::{Language, Script};
 use grenad::MergerBuilder;
 use heed::types::ByteSlice;
 use heed::RwTxn;
+use log::error;
+use obkv::{KvReader, KvWriter};
+use ordered_float::OrderedFloat;
 use roaring::RoaringBitmap;
 
 use super::helpers::{
-    self, merge_ignore_values, serialize_roaring_bitmap, valid_lmdb_key, CursorClonableMmap,
+    self, merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap, merge_ignore_values,
+    valid_lmdb_key, CursorClonableMmap,
 };
 use super::{ClonableMmap, MergeFn};
 use crate::distance::NDotProductPoint;
 use crate::error::UserError;
+use crate::external_documents_ids::{DocumentOperation, DocumentOperationKind};
 use crate::facet::FacetType;
+use crate::index::db_name::DOCUMENTS;
 use crate::index::Hnsw;
+use crate::update::del_add::{deladd_serialize_add_side, DelAdd, KvReaderDelAdd};
 use crate::update::facet::FacetsUpdate;
 use crate::update::index_documents::helpers::{as_cloneable_grenad, try_split_array_at};
-use crate::{lat_lng_to_xyz, CboRoaringBitmapCodec, DocumentId, GeoPoint, Index, Result, BEU32};
+use crate::{
+    lat_lng_to_xyz, DocumentId, FieldId, GeoPoint, Index, Result, SerializationError, BEU32,
+};
 
 pub(crate) enum TypedChunk {
     FieldIdDocidFacetStrings(grenad::Reader<CursorClonableMmap>),
     FieldIdDocidFacetNumbers(grenad::Reader<CursorClonableMmap>),
     Documents(grenad::Reader<CursorClonableMmap>),
-    FieldIdWordcountDocids(grenad::Reader<BufReader<File>>),
+    FieldIdWordCountDocids(grenad::Reader<BufReader<File>>),
-    NewDocumentsIds(RoaringBitmap),
     WordDocids {
         word_docids_reader: grenad::Reader<BufReader<File>>,
         exact_word_docids_reader: grenad::Reader<BufReader<File>>,
+        word_fid_docids_reader: grenad::Reader<BufReader<File>>,
     },
     WordPositionDocids(grenad::Reader<BufReader<File>>),
-    WordFidDocids(grenad::Reader<BufReader<File>>),
     WordPairProximityDocids(grenad::Reader<BufReader<File>>),
     FieldIdFacetStringDocids(grenad::Reader<BufReader<File>>),
     FieldIdFacetNumberDocids(grenad::Reader<BufReader<File>>),
@@ -43,7 +50,7 @@ pub(crate) enum TypedChunk {
     FieldIdFacetIsEmptyDocids(grenad::Reader<BufReader<File>>),
     GeoPoints(grenad::Reader<BufReader<File>>),
     VectorPoints(grenad::Reader<BufReader<File>>),
-    ScriptLanguageDocids(HashMap<(Script, Language), RoaringBitmap>),
+    ScriptLanguageDocids(HashMap<(Script, Language), (RoaringBitmap, RoaringBitmap)>),
 }
 
 impl TypedChunk {
@@ -58,23 +65,22 @@ impl TypedChunk {
             TypedChunk::Documents(grenad) => {
                 format!("Documents {{ number_of_entries: {} }}", grenad.len())
             }
-            TypedChunk::FieldIdWordcountDocids(grenad) => {
+            TypedChunk::FieldIdWordCountDocids(grenad) => {
                 format!("FieldIdWordcountDocids {{ number_of_entries: {} }}", grenad.len())
             }
-            TypedChunk::NewDocumentsIds(grenad) => {
+            TypedChunk::WordDocids {
-                format!("NewDocumentsIds {{ number_of_entries: {} }}", grenad.len())
+                word_docids_reader,
-            }
+                exact_word_docids_reader,
-            TypedChunk::WordDocids { word_docids_reader, exact_word_docids_reader } => format!(
+                word_fid_docids_reader,
-                "WordDocids {{ word_docids_reader: {}, exact_word_docids_reader: {} }}",
+            } => format!(
+                "WordDocids {{ word_docids_reader: {}, exact_word_docids_reader: {}, word_fid_docids_reader: {} }}",
                 word_docids_reader.len(),
-                exact_word_docids_reader.len()
+                exact_word_docids_reader.len(),
+                word_fid_docids_reader.len()
             ),
             TypedChunk::WordPositionDocids(grenad) => {
                 format!("WordPositionDocids {{ number_of_entries: {} }}", grenad.len())
             }
-            TypedChunk::WordFidDocids(grenad) => {
-                format!("WordFidDocids {{ number_of_entries: {} }}", grenad.len())
-            }
             TypedChunk::WordPairProximityDocids(grenad) => {
                 format!("WordPairProximityDocids {{ number_of_entries: {} }}", grenad.len())
             }
@@ -99,8 +105,8 @@ impl TypedChunk {
             TypedChunk::VectorPoints(grenad) => {
                 format!("VectorPoints {{ number_of_entries: {} }}", grenad.len())
             }
-            TypedChunk::ScriptLanguageDocids(grenad) => {
+            TypedChunk::ScriptLanguageDocids(sl_map) => {
-                format!("ScriptLanguageDocids {{ number_of_entries: {} }}", grenad.len())
+                format!("ScriptLanguageDocids {{ number_of_entries: {} }}", sl_map.len())
             }
         }
     }
@@ -119,34 +125,75 @@ pub(crate) fn write_typed_chunk_into_index(
     let mut is_merged_database = false;
     match typed_chunk {
         TypedChunk::Documents(obkv_documents_iter) => {
+            let mut operations: Vec<DocumentOperation> = Default::default();
+
+            let mut docids = index.documents_ids(wtxn)?;
             let mut cursor = obkv_documents_iter.into_cursor()?;
-            while let Some((key, value)) = cursor.move_on_next()? {
+            while let Some((key, reader)) = cursor.move_on_next()? {
-                index.documents.remap_types::<ByteSlice, ByteSlice>().put(wtxn, key, value)?;
+                let mut writer: KvWriter<_, FieldId> = KvWriter::memory();
+                let reader: KvReader<FieldId> = KvReader::new(reader);
+
+                let (document_id_bytes, external_id_bytes) = try_split_array_at(key)
+                    .ok_or(SerializationError::Decoding { db_name: Some(DOCUMENTS) })?;
+                let docid = DocumentId::from_be_bytes(document_id_bytes);
+                let external_id = std::str::from_utf8(external_id_bytes)?;
+
+                for (field_id, value) in reader.iter() {
+                    let del_add_reader = KvReaderDelAdd::new(value);
+
+                    if let Some(addition) = del_add_reader.get(DelAdd::Addition) {
+                        writer.insert(field_id, addition)?;
+                    }
+                }
+
+                let db = index.documents.remap_data_type::<ByteSlice>();
+
+                if !writer.is_empty() {
+                    db.put(wtxn, &BEU32::new(docid), &writer.into_inner().unwrap())?;
+                    operations.push(DocumentOperation {
+                        external_id: external_id.to_string(),
+                        internal_id: docid,
+                        kind: DocumentOperationKind::Create,
+                    });
+                    docids.insert(docid);
+                } else {
+                    db.delete(wtxn, &BEU32::new(docid))?;
+                    operations.push(DocumentOperation {
+                        external_id: external_id.to_string(),
+                        internal_id: docid,
+                        kind: DocumentOperationKind::Delete,
+                    });
+                    docids.remove(docid);
+                }
             }
+            let external_documents_docids = index.external_documents_ids();
+            external_documents_docids.apply(wtxn, operations)?;
+            index.put_documents_ids(wtxn, &docids)?;
         }
-        TypedChunk::FieldIdWordcountDocids(fid_word_count_docids_iter) => {
+        TypedChunk::FieldIdWordCountDocids(fid_word_count_docids_iter) => {
             append_entries_into_database(
                 fid_word_count_docids_iter,
                 &index.field_id_word_count_docids,
                 wtxn,
                 index_is_empty,
-                |value, _buffer| Ok(value),
+                deladd_serialize_add_side,
-                merge_cbo_roaring_bitmaps,
+                merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
             )?;
             is_merged_database = true;
         }
-        TypedChunk::NewDocumentsIds(documents_ids) => {
+        TypedChunk::WordDocids {
-            return Ok((documents_ids, is_merged_database))
+            word_docids_reader,
-        }
+            exact_word_docids_reader,
-        TypedChunk::WordDocids { word_docids_reader, exact_word_docids_reader } => {
+            word_fid_docids_reader,
+        } => {
             let word_docids_iter = unsafe { as_cloneable_grenad(&word_docids_reader) }?;
             append_entries_into_database(
                 word_docids_iter.clone(),
                 &index.word_docids,
                 wtxn,
                 index_is_empty,
-                |value, _buffer| Ok(value),
+                deladd_serialize_add_side,
-                merge_roaring_bitmaps,
+                merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
             )?;
 
             let exact_word_docids_iter = unsafe { as_cloneable_grenad(&exact_word_docids_reader) }?;
@@ -155,8 +202,18 @@ pub(crate) fn write_typed_chunk_into_index(
                 &index.exact_word_docids,
                 wtxn,
                 index_is_empty,
-                |value, _buffer| Ok(value),
+                deladd_serialize_add_side,
-                merge_roaring_bitmaps,
+                merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
+            )?;
+
+            let word_fid_docids_iter = unsafe { as_cloneable_grenad(&word_fid_docids_reader) }?;
+            append_entries_into_database(
+                word_fid_docids_iter,
+                &index.word_fid_docids,
+                wtxn,
+                index_is_empty,
+                deladd_serialize_add_side,
+                merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
             )?;
 
             // create fst from word docids
@@ -177,19 +234,8 @@ pub(crate) fn write_typed_chunk_into_index(
                 &index.word_position_docids,
                 wtxn,
                 index_is_empty,
-                |value, _buffer| Ok(value),
+                deladd_serialize_add_side,
-                merge_cbo_roaring_bitmaps,
+                merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
-            )?;
-            is_merged_database = true;
-        }
-        TypedChunk::WordFidDocids(word_fid_docids_iter) => {
-            append_entries_into_database(
-                word_fid_docids_iter,
-                &index.word_fid_docids,
-                wtxn,
-                index_is_empty,
-                |value, _buffer| Ok(value),
-                merge_cbo_roaring_bitmaps,
             )?;
             is_merged_database = true;
         }
@@ -209,8 +255,8 @@ pub(crate) fn write_typed_chunk_into_index(
                 &index.facet_id_exists_docids,
                 wtxn,
                 index_is_empty,
-                |value, _buffer| Ok(value),
+                deladd_serialize_add_side,
-                merge_cbo_roaring_bitmaps,
+                merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
             )?;
             is_merged_database = true;
         }
@@ -220,8 +266,8 @@ pub(crate) fn write_typed_chunk_into_index(
                 &index.facet_id_is_null_docids,
                 wtxn,
                 index_is_empty,
-                |value, _buffer| Ok(value),
+                deladd_serialize_add_side,
-                merge_cbo_roaring_bitmaps,
+                merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
             )?;
             is_merged_database = true;
         }
@@ -231,8 +277,8 @@ pub(crate) fn write_typed_chunk_into_index(
                 &index.facet_id_is_empty_docids,
                 wtxn,
                 index_is_empty,
-                |value, _buffer| Ok(value),
+                deladd_serialize_add_side,
-                merge_cbo_roaring_bitmaps,
+                merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
             )?;
             is_merged_database = true;
         }
@@ -242,8 +288,8 @@ pub(crate) fn write_typed_chunk_into_index(
                 &index.word_pair_proximity_docids,
                 wtxn,
                 index_is_empty,
-                |value, _buffer| Ok(value),
+                deladd_serialize_add_side,
-                merge_cbo_roaring_bitmaps,
+                merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
             )?;
             is_merged_database = true;
         }
@@ -252,8 +298,18 @@ pub(crate) fn write_typed_chunk_into_index(
                 index.field_id_docid_facet_f64s.remap_types::<ByteSlice, ByteSlice>();
             let mut cursor = fid_docid_facet_number.into_cursor()?;
             while let Some((key, value)) = cursor.move_on_next()? {
+                let reader = KvReaderDelAdd::new(value);
                 if valid_lmdb_key(key) {
-                    index_fid_docid_facet_numbers.put(wtxn, key, value)?;
+                    match (reader.get(DelAdd::Deletion), reader.get(DelAdd::Addition)) {
+                        (None, None) => {}
+                        (None, Some(new)) => index_fid_docid_facet_numbers.put(wtxn, key, new)?,
+                        (Some(_), None) => {
+                            index_fid_docid_facet_numbers.delete(wtxn, key)?;
+                        }
+                        (Some(_), Some(new)) => {
+                            index_fid_docid_facet_numbers.put(wtxn, key, new)?
+                        }
+                    }
                 }
             }
         }
@@ -262,8 +318,18 @@ pub(crate) fn write_typed_chunk_into_index(
                 index.field_id_docid_facet_strings.remap_types::<ByteSlice, ByteSlice>();
             let mut cursor = fid_docid_facet_string.into_cursor()?;
             while let Some((key, value)) = cursor.move_on_next()? {
+                let reader = KvReaderDelAdd::new(value);
                 if valid_lmdb_key(key) {
-                    index_fid_docid_facet_strings.put(wtxn, key, value)?;
+                    match (reader.get(DelAdd::Deletion), reader.get(DelAdd::Addition)) {
+                        (None, None) => {}
+                        (None, Some(new)) => index_fid_docid_facet_strings.put(wtxn, key, new)?,
+                        (Some(_), None) => {
+                            index_fid_docid_facet_strings.delete(wtxn, key)?;
+                        }
+                        (Some(_), Some(new)) => {
+                            index_fid_docid_facet_strings.put(wtxn, key, new)?
+                        }
+                    }
                 }
             }
         }
@@ -276,57 +342,86 @@ pub(crate) fn write_typed_chunk_into_index(
                 // convert the key back to a u32 (4 bytes)
                 let docid = key.try_into().map(DocumentId::from_be_bytes).unwrap();
 
-                // convert the latitude and longitude back to a f64 (8 bytes)
+                let deladd_obkv = KvReaderDelAdd::new(value);
-                let (lat, tail) = helpers::try_split_array_at::<u8, 8>(value).unwrap();
+                if let Some(value) = deladd_obkv.get(DelAdd::Deletion) {
-                let (lng, _) = helpers::try_split_array_at::<u8, 8>(tail).unwrap();
+                    let geopoint = extract_geo_point(value, docid);
-                let point = [f64::from_ne_bytes(lat), f64::from_ne_bytes(lng)];
+                    rtree.remove(&geopoint);
-                let xyz_point = lat_lng_to_xyz(&point);
+                    geo_faceted_docids.remove(docid);
-
+                }
-                rtree.insert(GeoPoint::new(xyz_point, (docid, point)));
+                if let Some(value) = deladd_obkv.get(DelAdd::Addition) {
-                geo_faceted_docids.insert(docid);
+                    let geopoint = extract_geo_point(value, docid);
+                    rtree.insert(geopoint);
+                    geo_faceted_docids.insert(docid);
+                }
             }
             index.put_geo_rtree(wtxn, &rtree)?;
             index.put_geo_faceted_documents_ids(wtxn, &geo_faceted_docids)?;
         }
         TypedChunk::VectorPoints(vector_points) => {
-            let (pids, mut points): (Vec<_>, Vec<_>) = match index.vector_hnsw(wtxn)? {
+            let mut vectors_set = HashSet::new();
-                Some(hnsw) => hnsw.iter().map(|(pid, point)| (pid, point.clone())).unzip(),
+            // We extract and store the previous vectors
-                None => Default::default(),
+            if let Some(hnsw) = index.vector_hnsw(wtxn)? {
-            };
+                for (pid, point) in hnsw.iter() {
-
+                    let pid_key = BEU32::new(pid.into_inner());
-            // Convert the PointIds into DocumentIds
+                    let docid = index.vector_id_docid.get(wtxn, &pid_key)?.unwrap().get();
-            let mut docids = Vec::new();
+                    let vector: Vec<_> = point.iter().copied().map(OrderedFloat).collect();
-            for pid in pids {
+                    vectors_set.insert((docid, vector));
-                let docid =
+                }
-                    index.vector_id_docid.get(wtxn, &BEU32::new(pid.into_inner()))?.unwrap();
-                docids.push(docid.get());
             }
 
-            let mut expected_dimensions = points.get(0).map(|p| p.len());
             let mut cursor = vector_points.into_cursor()?;
             while let Some((key, value)) = cursor.move_on_next()? {
                 // convert the key back to a u32 (4 bytes)
                 let (left, _index) = try_split_array_at(key).unwrap();
                 let docid = DocumentId::from_be_bytes(left);
-                // convert the vector back to a Vec<f32>
-                let vector: Vec<f32> = pod_collect_to_vec(value);
 
-                // TODO Inform the user about the document that has a wrong `_vectors`
+                let vector_deladd_obkv = KvReaderDelAdd::new(value);
-                let found = vector.len();
+                if let Some(value) = vector_deladd_obkv.get(DelAdd::Deletion) {
-                let expected = *expected_dimensions.get_or_insert(found);
+                    // convert the vector back to a Vec<f32>
-                if expected != found {
+                    let vector = pod_collect_to_vec(value).into_iter().map(OrderedFloat).collect();
-                    return Err(UserError::InvalidVectorDimensions { expected, found })?;
+                    let key = (docid, vector);
+                    if !vectors_set.remove(&key) {
+                        error!("Unable to delete the vector: {:?}", key.1);
+                    }
+                }
+                if let Some(value) = vector_deladd_obkv.get(DelAdd::Addition) {
+                    // convert the vector back to a Vec<f32>
+                    let vector = pod_collect_to_vec(value).into_iter().map(OrderedFloat).collect();
+                    vectors_set.insert((docid, vector));
                 }
-
-                points.push(NDotProductPoint::new(vector));
-                docids.push(docid);
             }
 
-            assert_eq!(docids.len(), points.len());
+            // Extract the most common vector dimension
+            let expected_dimension_size = {
+                let mut dims = HashMap::new();
+                vectors_set.iter().for_each(|(_, v)| *dims.entry(v.len()).or_insert(0) += 1);
+                dims.into_iter().max_by_key(|(_, count)| *count).map(|(len, _)| len)
+            };
+
+            // Ensure that the vector lengths are correct and
+            // prepare the vectors before inserting them in the HNSW.
+            let mut points = Vec::new();
+            let mut docids = Vec::new();
+            for (docid, vector) in vectors_set {
+                if expected_dimension_size.map_or(false, |expected| expected != vector.len()) {
+                    return Err(UserError::InvalidVectorDimensions {
+                        expected: expected_dimension_size.unwrap_or(vector.len()),
+                        found: vector.len(),
+                    }
+                    .into());
+                } else {
+                    let vector = vector.into_iter().map(OrderedFloat::into_inner).collect();
+                    points.push(NDotProductPoint::new(vector));
+                    docids.push(docid);
+                }
+            }
 
             let hnsw_length = points.len();
             let (new_hnsw, pids) = Hnsw::builder().build_hnsw(points);
 
+            assert_eq!(docids.len(), pids.len());
+
+            // Store the vectors in the point-docid relation database
             index.vector_id_docid.clear(wtxn)?;
             for (docid, pid) in docids.into_iter().zip(pids) {
                 index.vector_id_docid.put(
@@ -339,22 +434,25 @@ pub(crate) fn write_typed_chunk_into_index(
             log::debug!("There are {} entries in the HNSW so far", hnsw_length);
             index.put_vector_hnsw(wtxn, &new_hnsw)?;
         }
-        TypedChunk::ScriptLanguageDocids(hash_pair) => {
+        TypedChunk::ScriptLanguageDocids(sl_map) => {
-            let mut buffer = Vec::new();
+            for (key, (deletion, addition)) in sl_map {
-            for (key, value) in hash_pair {
+                let mut db_key_exists = false;
-                buffer.clear();
                 let final_value = match index.script_language_docids.get(wtxn, &key)? {
                     Some(db_values) => {
-                        let mut db_value_buffer = Vec::new();
+                        db_key_exists = true;
-                        serialize_roaring_bitmap(&db_values, &mut db_value_buffer)?;
+                        (db_values - deletion) | addition
-                        let mut new_value_buffer = Vec::new();
-                        serialize_roaring_bitmap(&value, &mut new_value_buffer)?;
-                        merge_roaring_bitmaps(&new_value_buffer, &db_value_buffer, &mut buffer)?;
-                        RoaringBitmap::deserialize_from(&buffer[..])?
                     }
-                    None => value,
+                    None => addition,
                 };
-                index.script_language_docids.put(wtxn, &key, &final_value)?;
+
+                if final_value.is_empty() {
+                    // If the database entry exists, delete it.
+                    if db_key_exists {
+                        index.script_language_docids.delete(wtxn, &key)?;
+                    }
+                } else {
+                    index.script_language_docids.put(wtxn, &key, &final_value)?;
+                }
             }
         }
     }
@@ -362,6 +460,15 @@ pub(crate) fn write_typed_chunk_into_index(
     Ok((RoaringBitmap::new(), is_merged_database))
 }
 
+/// Converts the latitude and longitude back to an xyz GeoPoint.
+fn extract_geo_point(value: &[u8], docid: DocumentId) -> GeoPoint {
+    let (lat, tail) = helpers::try_split_array_at::<u8, 8>(value).unwrap();
+    let (lng, _) = helpers::try_split_array_at::<u8, 8>(tail).unwrap();
+    let point = [f64::from_ne_bytes(lat), f64::from_ne_bytes(lng)];
+    let xyz_point = lat_lng_to_xyz(&point);
+    GeoPoint::new(xyz_point, (docid, point))
+}
+
 fn merge_word_docids_reader_into_fst(
     word_docids_iter: grenad::Reader<io::Cursor<ClonableMmap>>,
     exact_word_docids_iter: grenad::Reader<io::Cursor<ClonableMmap>>,
@@ -379,24 +486,6 @@ fn merge_word_docids_reader_into_fst(
     Ok(builder.into_set())
 }
 
-fn merge_roaring_bitmaps(new_value: &[u8], db_value: &[u8], buffer: &mut Vec<u8>) -> Result<()> {
-    let new_value = RoaringBitmap::deserialize_from(new_value)?;
-    let db_value = RoaringBitmap::deserialize_from(db_value)?;
-    let value = new_value | db_value;
-    Ok(serialize_roaring_bitmap(&value, buffer)?)
-}
-
-fn merge_cbo_roaring_bitmaps(
-    new_value: &[u8],
-    db_value: &[u8],
-    buffer: &mut Vec<u8>,
-) -> Result<()> {
-    Ok(CboRoaringBitmapCodec::merge_into(
-        &[Cow::Borrowed(db_value), Cow::Borrowed(new_value)],
-        buffer,
-    )?)
-}
-
 /// Write provided entries in database using serialize_value function.
 /// merge_values function is used if an entry already exist in the database.
 fn write_entries_into_database<R, K, V, FS, FM>(
@@ -410,7 +499,7 @@ fn write_entries_into_database<R, K, V, FS, FM>(
 where
     R: io::Read + io::Seek,
     FS: for<'a> Fn(&'a [u8], &'a mut Vec<u8>) -> Result<&'a [u8]>,
-    FM: Fn(&[u8], &[u8], &mut Vec<u8>) -> Result<()>,
+    FM: for<'a> Fn(&[u8], &[u8], &'a mut Vec<u8>) -> Result<Option<&'a [u8]>>,
 {
     puffin::profile_function!(format!("number of entries: {}", data.len()));
 
@@ -422,17 +511,19 @@ where
         if valid_lmdb_key(key) {
             buffer.clear();
             let value = if index_is_empty {
-                serialize_value(value, &mut buffer)?
+                Some(serialize_value(value, &mut buffer)?)
             } else {
                 match database.get(wtxn, key)? {
-                    Some(prev_value) => {
+                    Some(prev_value) => merge_values(value, prev_value, &mut buffer)?,
-                        merge_values(value, prev_value, &mut buffer)?;
+                    None => Some(serialize_value(value, &mut buffer)?),
-                        &buffer[..]
-                    }
-                    None => serialize_value(value, &mut buffer)?,
                 }
             };
-            database.put(wtxn, key, value)?;
+            match value {
+                Some(value) => database.put(wtxn, key, value)?,
+                None => {
+                    database.delete(wtxn, key)?;
+                }
+            }
         }
     }
 
@@ -454,7 +545,8 @@ fn append_entries_into_database<R, K, V, FS, FM>(
 where
     R: io::Read + io::Seek,
     FS: for<'a> Fn(&'a [u8], &'a mut Vec<u8>) -> Result<&'a [u8]>,
-    FM: Fn(&[u8], &[u8], &mut Vec<u8>) -> Result<()>,
+    FM: for<'a> Fn(&[u8], &[u8], &'a mut Vec<u8>) -> Result<Option<&'a [u8]>>,
+    K: for<'a> heed::BytesDecode<'a>,
 {
     puffin::profile_function!(format!("number of entries: {}", data.len()));
 
@@ -475,6 +567,12 @@ where
     let mut cursor = data.into_cursor()?;
     while let Some((key, value)) = cursor.move_on_next()? {
         if valid_lmdb_key(key) {
+            debug_assert!(
+                K::bytes_decode(key).is_some(),
+                "Couldn't decode key with the database decoder, key length: {} - key bytes: {:x?}",
+                key.len(),
+                &key
+            );
             buffer.clear();
             let value = serialize_value(value, &mut buffer)?;
             unsafe { database.append(key, value)? };

milli/src/update/mod.rs

@@ -1,6 +1,5 @@
 pub use self::available_documents_ids::AvailableDocumentsIds;
 pub use self::clear_documents::ClearDocuments;
-pub use self::delete_documents::{DeleteDocuments, DeletionStrategy, DocumentDeletionResult};
 pub use self::facet::bulk::FacetsUpdateBulk;
 pub use self::facet::incremental::FacetsUpdateIncrementalInner;
 pub use self::index_documents::{
@@ -9,10 +8,6 @@ pub use self::index_documents::{
     MergeFn,
 };
 pub use self::indexer_config::IndexerConfig;
-pub use self::prefix_word_pairs::{
-    PrefixWordPairsProximityDocids, MAX_LENGTH_FOR_PREFIX_PROXIMITY_DB,
-    MAX_PROXIMITY_FOR_PREFIX_PROXIMITY_DB,
-};
 pub use self::settings::{Setting, Settings};
 pub use self::update_step::UpdateIndexingStep;
 pub use self::word_prefix_docids::WordPrefixDocids;
@@ -21,11 +16,10 @@ pub use self::words_prefixes_fst::WordsPrefixesFst;
 
 mod available_documents_ids;
 mod clear_documents;
-mod delete_documents;
+pub(crate) mod del_add;
 pub(crate) mod facet;
 mod index_documents;
 mod indexer_config;
-mod prefix_word_pairs;
 mod settings;
 mod update_step;
 mod word_prefix_docids;

milli/src/update/prefix_word_pairs/mod.rs

@@ -1,579 +0,0 @@
-use std::borrow::Cow;
-use std::collections::HashSet;
-use std::io::{BufReader, BufWriter};
-
-use grenad::CompressionType;
-use heed::types::ByteSlice;
-
-use super::index_documents::{merge_cbo_roaring_bitmaps, CursorClonableMmap};
-use crate::{Index, Result};
-
-mod prefix_word;
-mod word_prefix;
-
-pub use prefix_word::index_prefix_word_database;
-pub use word_prefix::index_word_prefix_database;
-
-pub const MAX_PROXIMITY_FOR_PREFIX_PROXIMITY_DB: u8 = 4;
-pub const MAX_LENGTH_FOR_PREFIX_PROXIMITY_DB: usize = 2;
-
-pub struct PrefixWordPairsProximityDocids<'t, 'u, 'i> {
-    wtxn: &'t mut heed::RwTxn<'i, 'u>,
-    index: &'i Index,
-    max_proximity: u8,
-    max_prefix_length: usize,
-    chunk_compression_type: CompressionType,
-    chunk_compression_level: Option<u32>,
-}
-impl<'t, 'u, 'i> PrefixWordPairsProximityDocids<'t, 'u, 'i> {
-    pub fn new(
-        wtxn: &'t mut heed::RwTxn<'i, 'u>,
-        index: &'i Index,
-        chunk_compression_type: CompressionType,
-        chunk_compression_level: Option<u32>,
-    ) -> Self {
-        Self {
-            wtxn,
-            index,
-            max_proximity: MAX_PROXIMITY_FOR_PREFIX_PROXIMITY_DB,
-            max_prefix_length: MAX_LENGTH_FOR_PREFIX_PROXIMITY_DB,
-            chunk_compression_type,
-            chunk_compression_level,
-        }
-    }
-
-    #[logging_timer::time("WordPrefixPairProximityDocids::{}")]
-    pub fn execute<'a>(
-        self,
-        new_word_pair_proximity_docids: grenad::Reader<CursorClonableMmap>,
-        new_prefix_fst_words: &'a [String],
-        common_prefix_fst_words: &[&'a [String]],
-        del_prefix_fst_words: &HashSet<Vec<u8>>,
-    ) -> Result<()> {
-        puffin::profile_function!();
-
-        index_word_prefix_database(
-            self.wtxn,
-            self.index.word_pair_proximity_docids,
-            self.index.word_prefix_pair_proximity_docids,
-            self.max_proximity,
-            self.max_prefix_length,
-            new_word_pair_proximity_docids.clone(),
-            new_prefix_fst_words,
-            common_prefix_fst_words,
-            del_prefix_fst_words,
-            self.chunk_compression_type,
-            self.chunk_compression_level,
-        )?;
-
-        index_prefix_word_database(
-            self.wtxn,
-            self.index.word_pair_proximity_docids,
-            self.index.prefix_word_pair_proximity_docids,
-            self.max_proximity,
-            self.max_prefix_length,
-            new_word_pair_proximity_docids,
-            new_prefix_fst_words,
-            common_prefix_fst_words,
-            del_prefix_fst_words,
-            self.chunk_compression_type,
-            self.chunk_compression_level,
-        )?;
-
-        Ok(())
-    }
-}
-
-// This is adapted from `sorter_into_lmdb_database`
-pub fn insert_into_database(
-    wtxn: &mut heed::RwTxn,
-    database: heed::PolyDatabase,
-    new_key: &[u8],
-    new_value: &[u8],
-) -> Result<()> {
-    let mut iter = database.prefix_iter_mut::<_, ByteSlice, ByteSlice>(wtxn, new_key)?;
-    match iter.next().transpose()? {
-        Some((key, old_val)) if new_key == key => {
-            let val =
-                merge_cbo_roaring_bitmaps(key, &[Cow::Borrowed(old_val), Cow::Borrowed(new_value)])
-                    .map_err(|_| {
-                        // TODO just wrap this error?
-                        crate::error::InternalError::IndexingMergingKeys {
-                            process: "get-put-merge",
-                        }
-                    })?;
-            // safety: we use the new_key, not the one from the database iterator, to avoid undefined behaviour
-            unsafe { iter.put_current(new_key, &val)? };
-        }
-        _ => {
-            drop(iter);
-            database.put::<_, ByteSlice, ByteSlice>(wtxn, new_key, new_value)?;
-        }
-    }
-    Ok(())
-}
-
-// This is adapted from `sorter_into_lmdb_database` and `write_into_lmdb_database`,
-// but it uses `append` if the database is empty, and it assumes that the values in the
-// writer don't conflict with values in the database.
-pub fn write_into_lmdb_database_without_merging(
-    wtxn: &mut heed::RwTxn,
-    database: heed::PolyDatabase,
-    writer: grenad::Writer<BufWriter<std::fs::File>>,
-) -> Result<()> {
-    let file = writer.into_inner()?.into_inner().map_err(|err| err.into_error())?;
-    let reader = grenad::Reader::new(BufReader::new(file))?;
-    if database.is_empty(wtxn)? {
-        let mut out_iter = database.iter_mut::<_, ByteSlice, ByteSlice>(wtxn)?;
-        let mut cursor = reader.into_cursor()?;
-        while let Some((k, v)) = cursor.move_on_next()? {
-            // safety: the key comes from the grenad reader, not the database
-            unsafe { out_iter.append(k, v)? };
-        }
-    } else {
-        let mut cursor = reader.into_cursor()?;
-        while let Some((k, v)) = cursor.move_on_next()? {
-            database.put::<_, ByteSlice, ByteSlice>(wtxn, k, v)?;
-        }
-    }
-    Ok(())
-}
-
-#[cfg(test)]
-mod tests {
-    use std::io::Cursor;
-    use std::iter::FromIterator;
-
-    use roaring::RoaringBitmap;
-
-    use crate::db_snap;
-    use crate::documents::{DocumentsBatchBuilder, DocumentsBatchReader};
-    use crate::index::tests::TempIndex;
-    use crate::update::{DeleteDocuments, DeletionStrategy, IndexDocumentsMethod};
-
-    fn documents_with_enough_different_words_for_prefixes(
-        prefixes: &[&str],
-        start_id: usize,
-    ) -> Vec<crate::Object> {
-        let mut documents = Vec::new();
-        let mut id = start_id;
-        for prefix in prefixes {
-            for i in 0..50 {
-                documents.push(
-                    serde_json::json!({
-                        "id": id,
-                        "text": format!("{prefix}{i:x}"),
-                    })
-                    .as_object()
-                    .unwrap()
-                    .clone(),
-                );
-                id += 1;
-            }
-        }
-        documents
-    }
-
-    #[test]
-    fn add_new_documents() {
-        let mut index = TempIndex::new();
-        index.index_documents_config.words_prefix_threshold = Some(50);
-        index.index_documents_config.autogenerate_docids = true;
-
-        index
-            .update_settings(|settings| {
-                settings.set_searchable_fields(vec!["text".to_owned()]);
-            })
-            .unwrap();
-
-        let batch_reader_from_documents = |documents| {
-            let mut builder = DocumentsBatchBuilder::new(Vec::new());
-            for object in documents {
-                builder.append_json_object(&object).unwrap();
-            }
-            DocumentsBatchReader::from_reader(Cursor::new(builder.into_inner().unwrap())).unwrap()
-        };
-
-        let mut documents = documents_with_enough_different_words_for_prefixes(&["a", "be"], 0);
-        // now we add some documents where the text should populate the word_prefix_pair_proximity_docids database
-        documents.push(
-            serde_json::json!({
-                "id": "9000",
-                "text": "At an amazing and beautiful house"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-        documents.push(
-            serde_json::json!({
-                "id": "9001",
-                "text": "The bell rings at 5 am"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-
-        let documents = batch_reader_from_documents(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, word_prefix_pair_proximity_docids, "initial");
-        db_snap!(index, prefix_word_pair_proximity_docids, "initial");
-
-        let mut documents = documents_with_enough_different_words_for_prefixes(&["am", "an"], 100);
-        documents.push(
-            serde_json::json!({
-                "id": "9002",
-                "text": "At an extraordinary house"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-        let documents = batch_reader_from_documents(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, word_pair_proximity_docids, "update");
-        db_snap!(index, word_prefix_pair_proximity_docids, "update");
-        db_snap!(index, prefix_word_pair_proximity_docids, "update");
-    }
-    #[test]
-    fn batch_bug_3043() {
-        // https://github.com/meilisearch/meilisearch/issues/3043
-        let mut index = TempIndex::new();
-        index.index_documents_config.words_prefix_threshold = Some(50);
-        index.index_documents_config.autogenerate_docids = true;
-
-        index
-            .update_settings(|settings| {
-                settings.set_searchable_fields(vec!["text".to_owned()]);
-            })
-            .unwrap();
-
-        let batch_reader_from_documents = |documents| {
-            let mut builder = DocumentsBatchBuilder::new(Vec::new());
-            for object in documents {
-                builder.append_json_object(&object).unwrap();
-            }
-            DocumentsBatchReader::from_reader(Cursor::new(builder.into_inner().unwrap())).unwrap()
-        };
-
-        let mut documents = documents_with_enough_different_words_for_prefixes(&["y"], 0);
-        // now we add some documents where the text should populate the word_prefix_pair_proximity_docids database
-        documents.push(
-            serde_json::json!({
-                "text": "x y"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-        documents.push(
-            serde_json::json!({
-                "text": "x a y"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-
-        let documents = batch_reader_from_documents(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, word_pair_proximity_docids);
-        db_snap!(index, word_prefix_pair_proximity_docids);
-        db_snap!(index, prefix_word_pair_proximity_docids);
-    }
-
-    #[test]
-    fn hard_delete_and_reupdate() {
-        let mut index = TempIndex::new();
-        index.index_documents_config.words_prefix_threshold = Some(50);
-
-        index
-            .update_settings(|settings| {
-                settings.set_primary_key("id".to_owned());
-                settings.set_searchable_fields(vec!["text".to_owned()]);
-            })
-            .unwrap();
-
-        let batch_reader_from_documents = |documents| {
-            let mut builder = DocumentsBatchBuilder::new(Vec::new());
-            for object in documents {
-                builder.append_json_object(&object).unwrap();
-            }
-            DocumentsBatchReader::from_reader(Cursor::new(builder.into_inner().unwrap())).unwrap()
-        };
-
-        let mut documents = documents_with_enough_different_words_for_prefixes(&["a"], 0);
-        // now we add some documents where the text should populate the word_prefix_pair_proximity_docids database
-        documents.push(
-            serde_json::json!({
-                "id": 9000,
-                "text": "At an amazing and beautiful house"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-        documents.push(
-            serde_json::json!({
-                "id": 9001,
-                "text": "The bell rings at 5 am"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-
-        let documents = batch_reader_from_documents(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, documents_ids, "initial");
-        db_snap!(index, word_docids, "initial");
-        db_snap!(index, word_prefix_pair_proximity_docids, "initial");
-        db_snap!(index, prefix_word_pair_proximity_docids, "initial");
-
-        let mut wtxn = index.write_txn().unwrap();
-        let mut delete = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-        delete.strategy(DeletionStrategy::AlwaysHard);
-        delete.delete_documents(&RoaringBitmap::from_iter([50]));
-        delete.execute().unwrap();
-        wtxn.commit().unwrap();
-
-        db_snap!(index, documents_ids, "first_delete");
-        db_snap!(index, word_docids, "first_delete");
-        db_snap!(index, word_prefix_pair_proximity_docids, "first_delete");
-        db_snap!(index, prefix_word_pair_proximity_docids, "first_delete");
-
-        let mut wtxn = index.write_txn().unwrap();
-        let mut delete = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-        delete.strategy(DeletionStrategy::AlwaysHard);
-        delete.delete_documents(&RoaringBitmap::from_iter(0..50));
-        delete.execute().unwrap();
-        wtxn.commit().unwrap();
-
-        db_snap!(index, documents_ids, "second_delete");
-        db_snap!(index, word_docids, "second_delete");
-        db_snap!(index, word_prefix_pair_proximity_docids, "second_delete");
-        db_snap!(index, prefix_word_pair_proximity_docids, "second_delete");
-
-        let documents = documents_with_enough_different_words_for_prefixes(&["b"], 1000);
-        // now we add some documents where the text should populate the word_prefix_pair_proximity_docids database
-
-        index.add_documents(batch_reader_from_documents(documents)).unwrap();
-
-        db_snap!(index, documents_ids, "reupdate");
-        db_snap!(index, word_docids, "reupdate");
-        db_snap!(index, word_prefix_pair_proximity_docids, "reupdate");
-        db_snap!(index, prefix_word_pair_proximity_docids, "reupdate");
-    }
-
-    #[test]
-    fn soft_delete_and_reupdate() {
-        let mut index = TempIndex::new();
-        index.index_documents_config.words_prefix_threshold = Some(50);
-
-        index
-            .update_settings(|settings| {
-                settings.set_primary_key("id".to_owned());
-                settings.set_searchable_fields(vec!["text".to_owned()]);
-            })
-            .unwrap();
-
-        let batch_reader_from_documents = |documents| {
-            let mut builder = DocumentsBatchBuilder::new(Vec::new());
-            for object in documents {
-                builder.append_json_object(&object).unwrap();
-            }
-            DocumentsBatchReader::from_reader(Cursor::new(builder.into_inner().unwrap())).unwrap()
-        };
-
-        let mut documents = documents_with_enough_different_words_for_prefixes(&["a"], 0);
-        // now we add some documents where the text should populate the word_prefix_pair_proximity_docids database
-        documents.push(
-            serde_json::json!({
-                "id": 9000,
-                "text": "At an amazing and beautiful house"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-        documents.push(
-            serde_json::json!({
-                "id": 9001,
-                "text": "The bell rings at 5 am"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-
-        let documents = batch_reader_from_documents(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, documents_ids, "initial");
-        db_snap!(index, word_docids, "initial");
-        db_snap!(index, word_prefix_pair_proximity_docids, "initial");
-        db_snap!(index, prefix_word_pair_proximity_docids, "initial");
-
-        let mut wtxn = index.write_txn().unwrap();
-        let mut delete = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-        delete.strategy(DeletionStrategy::AlwaysSoft);
-        delete.delete_documents(&RoaringBitmap::from_iter([50]));
-        delete.execute().unwrap();
-        wtxn.commit().unwrap();
-
-        db_snap!(index, documents_ids, "first_delete");
-        db_snap!(index, word_docids, "first_delete");
-        db_snap!(index, word_prefix_pair_proximity_docids, "first_delete");
-        db_snap!(index, prefix_word_pair_proximity_docids, "first_delete");
-
-        let mut wtxn = index.write_txn().unwrap();
-        let mut delete = DeleteDocuments::new(&mut wtxn, &index).unwrap();
-        delete.strategy(DeletionStrategy::AlwaysSoft);
-
-        delete.delete_documents(&RoaringBitmap::from_iter(0..50));
-        delete.execute().unwrap();
-        wtxn.commit().unwrap();
-
-        db_snap!(index, documents_ids, "second_delete");
-        db_snap!(index, word_docids, "second_delete");
-        db_snap!(index, word_prefix_pair_proximity_docids, "second_delete");
-        db_snap!(index, prefix_word_pair_proximity_docids, "second_delete");
-
-        let documents = documents_with_enough_different_words_for_prefixes(&["b"], 1000);
-        // now we add some documents where the text should populate the word_prefix_pair_proximity_docids database
-
-        index.add_documents(batch_reader_from_documents(documents)).unwrap();
-
-        db_snap!(index, documents_ids, "reupdate");
-        db_snap!(index, word_docids, "reupdate");
-        db_snap!(index, word_prefix_pair_proximity_docids, "reupdate");
-        db_snap!(index, prefix_word_pair_proximity_docids, "reupdate");
-    }
-
-    #[test]
-    fn replace_soft_deletion() {
-        let mut index = TempIndex::new();
-        index.index_documents_config.words_prefix_threshold = Some(50);
-        index.index_documents_config.update_method = IndexDocumentsMethod::ReplaceDocuments;
-        index.index_documents_config.deletion_strategy = DeletionStrategy::AlwaysSoft;
-
-        index
-            .update_settings(|settings| {
-                settings.set_primary_key("id".to_owned());
-                settings.set_searchable_fields(vec!["text".to_owned()]);
-            })
-            .unwrap();
-
-        let batch_reader_from_documents = |documents| {
-            let mut builder = DocumentsBatchBuilder::new(Vec::new());
-            for object in documents {
-                builder.append_json_object(&object).unwrap();
-            }
-            DocumentsBatchReader::from_reader(Cursor::new(builder.into_inner().unwrap())).unwrap()
-        };
-
-        let mut documents = documents_with_enough_different_words_for_prefixes(&["a"], 0);
-        // now we add some documents where the text should populate the word_prefix_pair_proximity_docids database
-        documents.push(
-            serde_json::json!({
-                "id": 9000,
-                "text": "At an amazing house"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-        documents.push(
-            serde_json::json!({
-                "id": 9001,
-                "text": "The bell rings"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-
-        let documents = batch_reader_from_documents(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, documents_ids, "initial");
-        db_snap!(index, word_docids, "initial");
-        db_snap!(index, word_prefix_pair_proximity_docids, "initial");
-        db_snap!(index, prefix_word_pair_proximity_docids, "initial");
-
-        let documents = documents_with_enough_different_words_for_prefixes(&["b"], 0);
-        index.add_documents(batch_reader_from_documents(documents)).unwrap();
-
-        db_snap!(index, documents_ids, "replaced");
-        db_snap!(index, word_docids, "replaced");
-        db_snap!(index, word_prefix_pair_proximity_docids, "replaced");
-        db_snap!(index, prefix_word_pair_proximity_docids, "replaced");
-        db_snap!(index, soft_deleted_documents_ids, "replaced", @"[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, ]");
-    }
-
-    #[test]
-    fn replace_hard_deletion() {
-        let mut index = TempIndex::new();
-        index.index_documents_config.words_prefix_threshold = Some(50);
-        index.index_documents_config.deletion_strategy = DeletionStrategy::AlwaysHard;
-        index.index_documents_config.update_method = IndexDocumentsMethod::ReplaceDocuments;
-
-        index
-            .update_settings(|settings| {
-                settings.set_primary_key("id".to_owned());
-                settings.set_searchable_fields(vec!["text".to_owned()]);
-            })
-            .unwrap();
-
-        let batch_reader_from_documents = |documents| {
-            let mut builder = DocumentsBatchBuilder::new(Vec::new());
-            for object in documents {
-                builder.append_json_object(&object).unwrap();
-            }
-            DocumentsBatchReader::from_reader(Cursor::new(builder.into_inner().unwrap())).unwrap()
-        };
-
-        let mut documents = documents_with_enough_different_words_for_prefixes(&["a"], 0);
-        // now we add some documents where the text should populate the word_prefix_pair_proximity_docids database
-        documents.push(
-            serde_json::json!({
-                "id": 9000,
-                "text": "At an amazing house"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-        documents.push(
-            serde_json::json!({
-                "id": 9001,
-                "text": "The bell rings"
-            })
-            .as_object()
-            .unwrap()
-            .clone(),
-        );
-
-        let documents = batch_reader_from_documents(documents);
-        index.add_documents(documents).unwrap();
-
-        db_snap!(index, documents_ids, "initial");
-        db_snap!(index, word_docids, "initial");
-        db_snap!(index, word_prefix_pair_proximity_docids, "initial");
-        db_snap!(index, prefix_word_pair_proximity_docids, "initial");
-
-        let documents = documents_with_enough_different_words_for_prefixes(&["b"], 0);
-        index.add_documents(batch_reader_from_documents(documents)).unwrap();
-
-        db_snap!(index, documents_ids, "replaced");
-        db_snap!(index, word_docids, "replaced");
-        db_snap!(index, word_prefix_pair_proximity_docids, "replaced");
-        db_snap!(index, prefix_word_pair_proximity_docids, "replaced");
-        db_snap!(index, soft_deleted_documents_ids, "replaced", @"[]");
-    }
-}

milli/src/update/prefix_word_pairs/prefix_word.rs

@@ -1,182 +0,0 @@
-use std::borrow::Cow;
-use std::collections::{BTreeMap, HashSet};
-
-use grenad::CompressionType;
-use heed::types::ByteSlice;
-use heed::BytesDecode;
-use log::debug;
-
-use crate::update::index_documents::{create_writer, CursorClonableMmap};
-use crate::update::prefix_word_pairs::{
-    insert_into_database, write_into_lmdb_database_without_merging,
-};
-use crate::{CboRoaringBitmapCodec, Result, U8StrStrCodec, UncheckedU8StrStrCodec};
-
-#[allow(clippy::too_many_arguments)]
-#[logging_timer::time]
-pub fn index_prefix_word_database(
-    wtxn: &mut heed::RwTxn,
-    word_pair_proximity_docids: heed::Database<U8StrStrCodec, CboRoaringBitmapCodec>,
-    prefix_word_pair_proximity_docids: heed::Database<U8StrStrCodec, CboRoaringBitmapCodec>,
-    max_proximity: u8,
-    max_prefix_length: usize,
-    new_word_pair_proximity_docids: grenad::Reader<CursorClonableMmap>,
-    new_prefix_fst_words: &[String],
-    common_prefix_fst_words: &[&[String]],
-    del_prefix_fst_words: &HashSet<Vec<u8>>,
-    chunk_compression_type: CompressionType,
-    chunk_compression_level: Option<u32>,
-) -> Result<()> {
-    puffin::profile_function!();
-
-    let max_proximity = max_proximity - 1;
-    debug!("Computing and writing the word prefix pair proximity docids into LMDB on disk...");
-
-    let common_prefixes: Vec<_> = common_prefix_fst_words
-        .iter()
-        .flat_map(|s| s.iter())
-        .map(|s| s.as_str())
-        .filter(|s| s.len() <= max_prefix_length)
-        .collect();
-
-    for proximity in 1..max_proximity {
-        for prefix in common_prefixes.iter() {
-            let mut prefix_key = vec![proximity];
-            prefix_key.extend_from_slice(prefix.as_bytes());
-            let mut cursor = new_word_pair_proximity_docids.clone().into_prefix_iter(prefix_key)?;
-            // This is the core of the algorithm
-            execute_on_word_pairs_and_prefixes(
-                proximity,
-                prefix.as_bytes(),
-                // the next two arguments tell how to iterate over the new word pairs
-                &mut cursor,
-                |cursor| {
-                    if let Some((key, value)) = cursor.next()? {
-                        let (_, _, word2) = UncheckedU8StrStrCodec::bytes_decode(key)
-                            .ok_or(heed::Error::Decoding)?;
-                        Ok(Some((word2, value)))
-                    } else {
-                        Ok(None)
-                    }
-                },
-                // and this argument tells what to do with each new key (proximity, prefix, word2) and value (roaring bitmap)
-                |key, value| {
-                    insert_into_database(
-                        wtxn,
-                        *prefix_word_pair_proximity_docids.as_polymorph(),
-                        key,
-                        value,
-                    )
-                },
-            )?;
-        }
-    }
-
-    // Now we do the same thing with the new prefixes and all word pairs in the DB
-    let new_prefixes: Vec<_> = new_prefix_fst_words
-        .iter()
-        .map(|s| s.as_str())
-        .filter(|s| s.len() <= max_prefix_length)
-        .collect();
-
-    // Since we read the DB, we can't write to it directly, so we add each new (word1, prefix, proximity)
-    // element in an intermediary grenad
-    let mut writer =
-        create_writer(chunk_compression_type, chunk_compression_level, tempfile::tempfile()?);
-
-    for proximity in 1..max_proximity {
-        for prefix in new_prefixes.iter() {
-            let mut prefix_key = vec![proximity];
-            prefix_key.extend_from_slice(prefix.as_bytes());
-            let mut db_iter = word_pair_proximity_docids
-                .as_polymorph()
-                .prefix_iter::<_, ByteSlice, ByteSlice>(wtxn, prefix_key.as_slice())?
-                .remap_key_type::<UncheckedU8StrStrCodec>();
-            execute_on_word_pairs_and_prefixes(
-                proximity,
-                prefix.as_bytes(),
-                &mut db_iter,
-                |db_iter| {
-                    db_iter
-                        .next()
-                        .transpose()
-                        .map(|x| x.map(|((_, _, word2), value)| (word2, value)))
-                        .map_err(|e| e.into())
-                },
-                |key, value| writer.insert(key, value).map_err(|e| e.into()),
-            )?;
-            drop(db_iter);
-        }
-    }
-
-    // and then we write the grenad into the DB
-    // Since the grenad contains only new prefixes, we know in advance that none
-    // of its elements already exist in the DB, thus there is no need to specify
-    // how to merge conflicting elements
-    write_into_lmdb_database_without_merging(
-        wtxn,
-        *prefix_word_pair_proximity_docids.as_polymorph(),
-        writer,
-    )?;
-
-    // All of the word prefix pairs in the database that have a w2
-    // that is contained in the `suppr_pw` set must be removed as well.
-    if !del_prefix_fst_words.is_empty() {
-        let mut iter =
-            prefix_word_pair_proximity_docids.remap_data_type::<ByteSlice>().iter_mut(wtxn)?;
-        while let Some(((_, prefix, _), _)) = iter.next().transpose()? {
-            if del_prefix_fst_words.contains(prefix.as_bytes()) {
-                // Delete this entry as the w2 prefix is no more in the words prefix fst.
-                unsafe { iter.del_current()? };
-            }
-        }
-    }
-
-    Ok(())
-}
-
-/// This is the core of the algorithm to initialise the Prefix Word Pair Proximity Docids database.
-///
-/// Its arguments are:
-/// - an iterator over the words following the given `prefix` with the given `proximity`
-/// - a closure to describe how to handle the new computed (proximity, prefix, word2) elements
-fn execute_on_word_pairs_and_prefixes<I>(
-    proximity: u8,
-    prefix: &[u8],
-    iter: &mut I,
-    mut next_word2_and_docids: impl for<'a> FnMut(&'a mut I) -> Result<Option<(&'a [u8], &'a [u8])>>,
-    mut insert: impl for<'a> FnMut(&'a [u8], &'a [u8]) -> Result<()>,
-) -> Result<()> {
-    let mut batch: BTreeMap<Vec<u8>, Vec<Cow<'static, [u8]>>> = BTreeMap::default();
-
-    // Memory usage check:
-    // The content of the loop will be called for each `word2` that follows a word beginning
-    // with `prefix` with the given proximity.
-    // In practice, I don't think the batch can ever get too big.
-    while let Some((word2, docids)) = next_word2_and_docids(iter)? {
-        let entry = batch.entry(word2.to_owned()).or_default();
-        entry.push(Cow::Owned(docids.to_owned()));
-    }
-
-    let mut key_buffer = Vec::with_capacity(512);
-    key_buffer.push(proximity);
-    key_buffer.extend_from_slice(prefix);
-    key_buffer.push(0);
-
-    let mut value_buffer = Vec::with_capacity(65_536);
-
-    for (word2, docids) in batch {
-        key_buffer.truncate(prefix.len() + 2);
-        value_buffer.clear();
-
-        key_buffer.extend_from_slice(&word2);
-        let data = if docids.len() > 1 {
-            CboRoaringBitmapCodec::merge_into(&docids, &mut value_buffer)?;
-            value_buffer.as_slice()
-        } else {
-            &docids[0]
-        };
-        insert(key_buffer.as_slice(), data)?;
-    }
-    Ok(())
-}

milli/src/update/prefix_word_pairs/snapshots/mod.rs/add_new_documents/initial/prefix_word_pair_proximity_docids.snap

@@ -1,20 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  a    5                [101, ]
-1  a    amazing          [100, ]
-1  a    an               [100, ]
-1  a    and              [100, ]
-1  a    beautiful        [100, ]
-1  b    house            [100, ]
-1  b    rings            [101, ]
-1  be   house            [100, ]
-1  be   rings            [101, ]
-2  a    am               [101, ]
-2  a    amazing          [100, ]
-2  a    and              [100, ]
-2  a    beautiful        [100, ]
-2  a    house            [100, ]
-2  b    at               [101, ]
-2  be   at               [101, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/add_new_documents/initial/word_prefix_pair_proximity_docids.snap

@@ -1,23 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  5                a    [101, ]
-1  amazing          a    [100, ]
-1  an               a    [100, ]
-1  and              b    [100, ]
-1  and              be   [100, ]
-1  at               a    [100, ]
-1  rings            a    [101, ]
-1  the              b    [101, ]
-1  the              be   [101, ]
-2  amazing          b    [100, ]
-2  amazing          be   [100, ]
-2  an               a    [100, ]
-2  at               a    [100, 101, ]
-2  bell             a    [101, ]
-3  an               b    [100, ]
-3  an               be   [100, ]
-3  at               a    [100, ]
-3  rings            a    [101, ]
-3  the              a    [101, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/add_new_documents/update/prefix_word_pair_proximity_docids.snap

@@ -1,29 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  a    5                [101, ]
-1  a    amazing          [100, ]
-1  a    an               [100, 202, ]
-1  a    and              [100, ]
-1  a    beautiful        [100, ]
-1  a    extraordinary    [202, ]
-1  am   and              [100, ]
-1  an   amazing          [100, ]
-1  an   beautiful        [100, ]
-1  an   extraordinary    [202, ]
-1  b    house            [100, ]
-1  b    rings            [101, ]
-1  be   house            [100, ]
-1  be   rings            [101, ]
-2  a    am               [101, ]
-2  a    amazing          [100, ]
-2  a    and              [100, ]
-2  a    beautiful        [100, ]
-2  a    extraordinary    [202, ]
-2  a    house            [100, 202, ]
-2  am   beautiful        [100, ]
-2  an   and              [100, ]
-2  an   house            [100, 202, ]
-2  b    at               [101, ]
-2  be   at               [101, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/add_new_documents/update/word_pair_proximity_docids.snap

@@ -1,33 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  5                am               [101, ]
-1  amazing          and              [100, ]
-1  an               amazing          [100, ]
-1  an               extraordinary    [202, ]
-1  and              beautiful        [100, ]
-1  at               5                [101, ]
-1  at               an               [100, 202, ]
-1  beautiful        house            [100, ]
-1  bell             rings            [101, ]
-1  extraordinary    house            [202, ]
-1  rings            at               [101, ]
-1  the              bell             [101, ]
-2  amazing          beautiful        [100, ]
-2  an               and              [100, ]
-2  an               house            [202, ]
-2  and              house            [100, ]
-2  at               am               [101, ]
-2  at               amazing          [100, ]
-2  at               extraordinary    [202, ]
-2  bell             at               [101, ]
-2  rings            5                [101, ]
-2  the              rings            [101, ]
-3  amazing          house            [100, ]
-3  an               beautiful        [100, ]
-3  at               and              [100, ]
-3  at               house            [202, ]
-3  bell             5                [101, ]
-3  rings            am               [101, ]
-3  the              at               [101, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/add_new_documents/update/word_prefix_pair_proximity_docids.snap

@@ -1,31 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  5                a    [101, ]
-1  5                am   [101, ]
-1  amazing          a    [100, ]
-1  amazing          an   [100, ]
-1  an               a    [100, ]
-1  an               am   [100, ]
-1  and              b    [100, ]
-1  and              be   [100, ]
-1  at               a    [100, 202, ]
-1  at               an   [100, 202, ]
-1  rings            a    [101, ]
-1  the              b    [101, ]
-1  the              be   [101, ]
-2  amazing          b    [100, ]
-2  amazing          be   [100, ]
-2  an               a    [100, ]
-2  an               an   [100, ]
-2  at               a    [100, 101, ]
-2  at               am   [100, 101, ]
-2  bell             a    [101, ]
-3  an               b    [100, ]
-3  an               be   [100, ]
-3  at               a    [100, ]
-3  at               an   [100, ]
-3  rings            a    [101, ]
-3  rings            am   [101, ]
-3  the              a    [101, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/batch_bug_3043/prefix_word_pair_proximity_docids.snap

@@ -1,4 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/batch_bug_3043/word_pair_proximity_docids.snap

@@ -1,8 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  a                y                [51, ]
-1  x                a                [51, ]
-1  x                y                [50, ]
-2  x                y                [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/batch_bug_3043/word_prefix_pair_proximity_docids.snap

@@ -1,7 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  a                y    [51, ]
-1  x                y    [50, ]
-2  x                y    [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/first_delete/documents_ids.snap

@@ -1,4 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, ]

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/first_delete/prefix_word_pair_proximity_docids.snap

@@ -1,6 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  a    5                [51, ]
-2  a    am               [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/first_delete/word_docids.snap

@@ -1,60 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-5                [51, ]
-a0               [0, ]
-a1               [1, ]
-a10              [16, ]
-a11              [17, ]
-a12              [18, ]
-a13              [19, ]
-a14              [20, ]
-a15              [21, ]
-a16              [22, ]
-a17              [23, ]
-a18              [24, ]
-a19              [25, ]
-a1a              [26, ]
-a1b              [27, ]
-a1c              [28, ]
-a1d              [29, ]
-a1e              [30, ]
-a1f              [31, ]
-a2               [2, ]
-a20              [32, ]
-a21              [33, ]
-a22              [34, ]
-a23              [35, ]
-a24              [36, ]
-a25              [37, ]
-a26              [38, ]
-a27              [39, ]
-a28              [40, ]
-a29              [41, ]
-a2a              [42, ]
-a2b              [43, ]
-a2c              [44, ]
-a2d              [45, ]
-a2e              [46, ]
-a2f              [47, ]
-a3               [3, ]
-a30              [48, ]
-a31              [49, ]
-a4               [4, ]
-a5               [5, ]
-a6               [6, ]
-a7               [7, ]
-a8               [8, ]
-a9               [9, ]
-aa               [10, ]
-ab               [11, ]
-ac               [12, ]
-ad               [13, ]
-ae               [14, ]
-af               [15, ]
-am               [51, ]
-at               [51, ]
-bell             [51, ]
-rings            [51, ]
-the              [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/first_delete/word_prefix_pair_proximity_docids.snap

@@ -1,10 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  5                a    [51, ]
-1  rings            a    [51, ]
-2  at               a    [51, ]
-2  bell             a    [51, ]
-3  rings            a    [51, ]
-3  the              a    [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/initial/documents_ids.snap

@@ -1,4 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, ]

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/initial/prefix_word_pair_proximity_docids.snap

@@ -1,14 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  a    5                [51, ]
-1  a    amazing          [50, ]
-1  a    an               [50, ]
-1  a    and              [50, ]
-1  a    beautiful        [50, ]
-2  a    am               [51, ]
-2  a    amazing          [50, ]
-2  a    and              [50, ]
-2  a    beautiful        [50, ]
-2  a    house            [50, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/initial/word_docids.snap

@@ -1,65 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-5                [51, ]
-a0               [0, ]
-a1               [1, ]
-a10              [16, ]
-a11              [17, ]
-a12              [18, ]
-a13              [19, ]
-a14              [20, ]
-a15              [21, ]
-a16              [22, ]
-a17              [23, ]
-a18              [24, ]
-a19              [25, ]
-a1a              [26, ]
-a1b              [27, ]
-a1c              [28, ]
-a1d              [29, ]
-a1e              [30, ]
-a1f              [31, ]
-a2               [2, ]
-a20              [32, ]
-a21              [33, ]
-a22              [34, ]
-a23              [35, ]
-a24              [36, ]
-a25              [37, ]
-a26              [38, ]
-a27              [39, ]
-a28              [40, ]
-a29              [41, ]
-a2a              [42, ]
-a2b              [43, ]
-a2c              [44, ]
-a2d              [45, ]
-a2e              [46, ]
-a2f              [47, ]
-a3               [3, ]
-a30              [48, ]
-a31              [49, ]
-a4               [4, ]
-a5               [5, ]
-a6               [6, ]
-a7               [7, ]
-a8               [8, ]
-a9               [9, ]
-aa               [10, ]
-ab               [11, ]
-ac               [12, ]
-ad               [13, ]
-ae               [14, ]
-af               [15, ]
-am               [51, ]
-amazing          [50, ]
-an               [50, ]
-and              [50, ]
-at               [50, 51, ]
-beautiful        [50, ]
-bell             [51, ]
-house            [50, ]
-rings            [51, ]
-the              [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/initial/word_prefix_pair_proximity_docids.snap

@@ -1,15 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  5                a    [51, ]
-1  amazing          a    [50, ]
-1  an               a    [50, ]
-1  at               a    [50, ]
-1  rings            a    [51, ]
-2  an               a    [50, ]
-2  at               a    [50, 51, ]
-2  bell             a    [51, ]
-3  at               a    [50, ]
-3  rings            a    [51, ]
-3  the              a    [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/reupdate/documents_ids.snap

@@ -1,4 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, ]

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/reupdate/prefix_word_pair_proximity_docids.snap

@@ -1,6 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  b    rings            [51, ]
-2  b    at               [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/reupdate/word_docids.snap

@@ -1,60 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-5                [51, ]
-am               [51, ]
-at               [51, ]
-b0               [0, ]
-b1               [1, ]
-b10              [16, ]
-b11              [17, ]
-b12              [18, ]
-b13              [19, ]
-b14              [20, ]
-b15              [21, ]
-b16              [22, ]
-b17              [23, ]
-b18              [24, ]
-b19              [25, ]
-b1a              [26, ]
-b1b              [27, ]
-b1c              [28, ]
-b1d              [29, ]
-b1e              [30, ]
-b1f              [31, ]
-b2               [2, ]
-b20              [32, ]
-b21              [33, ]
-b22              [34, ]
-b23              [35, ]
-b24              [36, ]
-b25              [37, ]
-b26              [38, ]
-b27              [39, ]
-b28              [40, ]
-b29              [41, ]
-b2a              [42, ]
-b2b              [43, ]
-b2c              [44, ]
-b2d              [45, ]
-b2e              [46, ]
-b2f              [47, ]
-b3               [3, ]
-b30              [48, ]
-b31              [49, ]
-b4               [4, ]
-b5               [5, ]
-b6               [6, ]
-b7               [7, ]
-b8               [8, ]
-b9               [9, ]
-ba               [10, ]
-bb               [11, ]
-bc               [12, ]
-bd               [13, ]
-be               [14, ]
-bell             [51, ]
-bf               [15, ]
-rings            [51, ]
-the              [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/reupdate/word_prefix_pair_proximity_docids.snap

@@ -1,5 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  the              b    [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/second_delete/documents_ids.snap

@@ -1,4 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-[51, ]

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/second_delete/prefix_word_pair_proximity_docids.snap

@@ -1,6 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  a    5                [51, ]
-2  a    am               [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/second_delete/word_docids.snap

@@ -1,10 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-5                [51, ]
-am               [51, ]
-at               [51, ]
-bell             [51, ]
-rings            [51, ]
-the              [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/hard_delete_and_reupdate/second_delete/word_prefix_pair_proximity_docids.snap

@@ -1,10 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  5                a    [51, ]
-1  rings            a    [51, ]
-2  at               a    [51, ]
-2  bell             a    [51, ]
-3  rings            a    [51, ]
-3  the              a    [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/replace_hard_deletion/initial/documents_ids.snap

@@ -1,4 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, ]

milli/src/update/prefix_word_pairs/snapshots/mod.rs/replace_hard_deletion/initial/prefix_word_pair_proximity_docids.snap

@@ -1,9 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  a    amazing          [50, ]
-1  a    an               [50, ]
-1  a    house            [50, ]
-2  a    amazing          [50, ]
-2  a    house            [50, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/replace_hard_deletion/initial/word_docids.snap

@@ -1,61 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-a0               [0, ]
-a1               [1, ]
-a10              [16, ]
-a11              [17, ]
-a12              [18, ]
-a13              [19, ]
-a14              [20, ]
-a15              [21, ]
-a16              [22, ]
-a17              [23, ]
-a18              [24, ]
-a19              [25, ]
-a1a              [26, ]
-a1b              [27, ]
-a1c              [28, ]
-a1d              [29, ]
-a1e              [30, ]
-a1f              [31, ]
-a2               [2, ]
-a20              [32, ]
-a21              [33, ]
-a22              [34, ]
-a23              [35, ]
-a24              [36, ]
-a25              [37, ]
-a26              [38, ]
-a27              [39, ]
-a28              [40, ]
-a29              [41, ]
-a2a              [42, ]
-a2b              [43, ]
-a2c              [44, ]
-a2d              [45, ]
-a2e              [46, ]
-a2f              [47, ]
-a3               [3, ]
-a30              [48, ]
-a31              [49, ]
-a4               [4, ]
-a5               [5, ]
-a6               [6, ]
-a7               [7, ]
-a8               [8, ]
-a9               [9, ]
-aa               [10, ]
-ab               [11, ]
-ac               [12, ]
-ad               [13, ]
-ae               [14, ]
-af               [15, ]
-amazing          [50, ]
-an               [50, ]
-at               [50, ]
-bell             [51, ]
-house            [50, ]
-rings            [51, ]
-the              [51, ]
-

milli/src/update/prefix_word_pairs/snapshots/mod.rs/replace_hard_deletion/initial/word_prefix_pair_proximity_docids.snap

@@ -1,7 +0,0 @@
----
-source: milli/src/update/prefix_word_pairs/mod.rs
----
-1  an               a    [50, ]
-1  at               a    [50, ]
-2  at               a    [50, ]
-