fix the addition + deletion bug

Cargo.lock

@@ -359,6 +359,15 @@ dependencies = [
  "backtrace",
 ]
 
+[[package]]
+name = "arbitrary"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2d098ff73c1ca148721f37baad5ea6a465a13f9573aba8641fbbbae8164a54e"
+dependencies = [
+ "derive_arbitrary",
+]
+
 [[package]]
 name = "assert-json-diff"
 version = "2.0.2"
@@ -1096,6 +1105,17 @@ dependencies = [
  "syn 1.0.109",
 ]
 
+[[package]]
+name = "derive_arbitrary"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f3cdeb9ec472d588e539a818b2dee436825730da08ad0017c4b1a17676bdc8b7"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+]
+
 [[package]]
 name = "derive_builder"
 version = "0.12.0"
@@ -2711,6 +2731,7 @@ dependencies = [
 name = "milli"
 version = "1.2.0"
 dependencies = [
+ "arbitrary",
  "big_s",
  "bimap",
  "bincode",
@@ -2722,6 +2743,7 @@ dependencies = [
  "csv",
  "deserr",
  "either",
+ "fastrand",
  "filter-parser",
  "flatten-serde-json",
  "fst",

index-scheduler/src/snapshots/lib.rs/document_addition_and_document_deletion/after_processing_the_batch.snap

@@ -0,0 +1,43 @@
+---
+source: index-scheduler/src/lib.rs
+---
+### Autobatching Enabled = true
+### Processing Tasks:
+[]
+----------------------------------------------------------------------
+### All Tasks:
+0 {uid: 0, status: succeeded, details: { received_documents: 3, indexed_documents: Some(3) }, kind: DocumentAdditionOrUpdate { index_uid: "doggos", primary_key: Some("id"), method: ReplaceDocuments, content_file: 00000000-0000-0000-0000-000000000000, documents_count: 3, allow_index_creation: true }}
+1 {uid: 1, status: succeeded, details: { received_document_ids: 2, deleted_documents: Some(2) }, kind: DocumentDeletion { index_uid: "doggos", documents_ids: ["1", "2"] }}
+----------------------------------------------------------------------
+### Status:
+enqueued []
+succeeded [0,1,]
+----------------------------------------------------------------------
+### Kind:
+"documentAdditionOrUpdate" [0,]
+"documentDeletion" [1,]
+----------------------------------------------------------------------
+### Index Tasks:
+doggos [0,1,]
+----------------------------------------------------------------------
+### Index Mapper:
+doggos: { number_of_documents: 1, field_distribution: {"doggo": 1, "id": 1} }
+
+----------------------------------------------------------------------
+### Canceled By:
+
+----------------------------------------------------------------------
+### Enqueued At:
+[timestamp] [0,]
+[timestamp] [1,]
+----------------------------------------------------------------------
+### Started At:
+[timestamp] [0,1,]
+----------------------------------------------------------------------
+### Finished At:
+[timestamp] [0,1,]
+----------------------------------------------------------------------
+### File Store:
+
+----------------------------------------------------------------------
+

index-scheduler/src/snapshots/lib.rs/document_addition_and_document_deletion/documents.snap

@@ -0,0 +1,9 @@
+---
+source: index-scheduler/src/lib.rs
+---
+[
+  {
+    "id": 3,
+    "doggo": "bork"
+  }
+]

index-scheduler/src/snapshots/lib.rs/document_addition_and_document_deletion/registered_the_first_task.snap

@@ -0,0 +1,37 @@
+---
+source: index-scheduler/src/lib.rs
+---
+### Autobatching Enabled = true
+### Processing Tasks:
+[]
+----------------------------------------------------------------------
+### All Tasks:
+0 {uid: 0, status: enqueued, details: { received_documents: 3, indexed_documents: None }, kind: DocumentAdditionOrUpdate { index_uid: "doggos", primary_key: Some("id"), method: ReplaceDocuments, content_file: 00000000-0000-0000-0000-000000000000, documents_count: 3, allow_index_creation: true }}
+----------------------------------------------------------------------
+### Status:
+enqueued [0,]
+----------------------------------------------------------------------
+### Kind:
+"documentAdditionOrUpdate" [0,]
+----------------------------------------------------------------------
+### Index Tasks:
+doggos [0,]
+----------------------------------------------------------------------
+### Index Mapper:
+
+----------------------------------------------------------------------
+### Canceled By:
+
+----------------------------------------------------------------------
+### Enqueued At:
+[timestamp] [0,]
+----------------------------------------------------------------------
+### Started At:
+----------------------------------------------------------------------
+### Finished At:
+----------------------------------------------------------------------
+### File Store:
+00000000-0000-0000-0000-000000000000
+
+----------------------------------------------------------------------
+

index-scheduler/src/snapshots/lib.rs/document_addition_and_document_deletion/registered_the_second_task.snap

@@ -0,0 +1,40 @@
+---
+source: index-scheduler/src/lib.rs
+---
+### Autobatching Enabled = true
+### Processing Tasks:
+[]
+----------------------------------------------------------------------
+### All Tasks:
+0 {uid: 0, status: enqueued, details: { received_documents: 3, indexed_documents: None }, kind: DocumentAdditionOrUpdate { index_uid: "doggos", primary_key: Some("id"), method: ReplaceDocuments, content_file: 00000000-0000-0000-0000-000000000000, documents_count: 3, allow_index_creation: true }}
+1 {uid: 1, status: enqueued, details: { received_document_ids: 2, deleted_documents: None }, kind: DocumentDeletion { index_uid: "doggos", documents_ids: ["1", "2"] }}
+----------------------------------------------------------------------
+### Status:
+enqueued [0,1,]
+----------------------------------------------------------------------
+### Kind:
+"documentAdditionOrUpdate" [0,]
+"documentDeletion" [1,]
+----------------------------------------------------------------------
+### Index Tasks:
+doggos [0,1,]
+----------------------------------------------------------------------
+### Index Mapper:
+
+----------------------------------------------------------------------
+### Canceled By:
+
+----------------------------------------------------------------------
+### Enqueued At:
+[timestamp] [0,]
+[timestamp] [1,]
+----------------------------------------------------------------------
+### Started At:
+----------------------------------------------------------------------
+### Finished At:
+----------------------------------------------------------------------
+### File Store:
+00000000-0000-0000-0000-000000000000
+
+----------------------------------------------------------------------
+

index-scheduler/src/snapshots/lib.rs/document_deletion_and_document_addition/after_failing_the_deletion.snap

@@ -0,0 +1,43 @@
+---
+source: index-scheduler/src/lib.rs
+---
+### Autobatching Enabled = true
+### Processing Tasks:
+[]
+----------------------------------------------------------------------
+### All Tasks:
+0 {uid: 0, status: failed, error: ResponseError { code: 200, message: "Index `doggos` not found.", error_code: "index_not_found", error_type: "invalid_request", error_link: "https://docs.meilisearch.com/errors#index_not_found" }, details: { received_document_ids: 2, deleted_documents: Some(0) }, kind: DocumentDeletion { index_uid: "doggos", documents_ids: ["1", "2"] }}
+1 {uid: 1, status: enqueued, details: { received_documents: 3, indexed_documents: None }, kind: DocumentAdditionOrUpdate { index_uid: "doggos", primary_key: Some("id"), method: ReplaceDocuments, content_file: 00000000-0000-0000-0000-000000000000, documents_count: 3, allow_index_creation: true }}
+----------------------------------------------------------------------
+### Status:
+enqueued [1,]
+failed [0,]
+----------------------------------------------------------------------
+### Kind:
+"documentAdditionOrUpdate" [1,]
+"documentDeletion" [0,]
+----------------------------------------------------------------------
+### Index Tasks:
+doggos [0,1,]
+----------------------------------------------------------------------
+### Index Mapper:
+
+----------------------------------------------------------------------
+### Canceled By:
+
+----------------------------------------------------------------------
+### Enqueued At:
+[timestamp] [0,]
+[timestamp] [1,]
+----------------------------------------------------------------------
+### Started At:
+[timestamp] [0,]
+----------------------------------------------------------------------
+### Finished At:
+[timestamp] [0,]
+----------------------------------------------------------------------
+### File Store:
+00000000-0000-0000-0000-000000000000
+
+----------------------------------------------------------------------
+

index-scheduler/src/snapshots/lib.rs/document_deletion_and_document_addition/after_last_successful_addition.snap

@@ -0,0 +1,46 @@
+---
+source: index-scheduler/src/lib.rs
+---
+### Autobatching Enabled = true
+### Processing Tasks:
+[]
+----------------------------------------------------------------------
+### All Tasks:
+0 {uid: 0, status: failed, error: ResponseError { code: 200, message: "Index `doggos` not found.", error_code: "index_not_found", error_type: "invalid_request", error_link: "https://docs.meilisearch.com/errors#index_not_found" }, details: { received_document_ids: 2, deleted_documents: Some(0) }, kind: DocumentDeletion { index_uid: "doggos", documents_ids: ["1", "2"] }}
+1 {uid: 1, status: succeeded, details: { received_documents: 3, indexed_documents: Some(3) }, kind: DocumentAdditionOrUpdate { index_uid: "doggos", primary_key: Some("id"), method: ReplaceDocuments, content_file: 00000000-0000-0000-0000-000000000000, documents_count: 3, allow_index_creation: true }}
+----------------------------------------------------------------------
+### Status:
+enqueued []
+succeeded [1,]
+failed [0,]
+----------------------------------------------------------------------
+### Kind:
+"documentAdditionOrUpdate" [1,]
+"documentDeletion" [0,]
+----------------------------------------------------------------------
+### Index Tasks:
+doggos [0,1,]
+----------------------------------------------------------------------
+### Index Mapper:
+doggos: { number_of_documents: 3, field_distribution: {"catto": 1, "doggo": 2, "id": 3} }
+
+----------------------------------------------------------------------
+### Canceled By:
+
+----------------------------------------------------------------------
+### Enqueued At:
+[timestamp] [0,]
+[timestamp] [1,]
+----------------------------------------------------------------------
+### Started At:
+[timestamp] [0,]
+[timestamp] [1,]
+----------------------------------------------------------------------
+### Finished At:
+[timestamp] [0,]
+[timestamp] [1,]
+----------------------------------------------------------------------
+### File Store:
+
+----------------------------------------------------------------------
+

index-scheduler/src/snapshots/lib.rs/document_deletion_and_document_addition/documents.snap

@@ -0,0 +1,17 @@
+---
+source: index-scheduler/src/lib.rs
+---
+[
+  {
+    "id": 1,
+    "doggo": "jean bob"
+  },
+  {
+    "id": 2,
+    "catto": "jorts"
+  },
+  {
+    "id": 3,
+    "doggo": "bork"
+  }
+]

index-scheduler/src/snapshots/lib.rs/document_deletion_and_document_addition/registered_the_first_task.snap

@@ -0,0 +1,36 @@
+---
+source: index-scheduler/src/lib.rs
+---
+### Autobatching Enabled = true
+### Processing Tasks:
+[]
+----------------------------------------------------------------------
+### All Tasks:
+0 {uid: 0, status: enqueued, details: { received_document_ids: 2, deleted_documents: None }, kind: DocumentDeletion { index_uid: "doggos", documents_ids: ["1", "2"] }}
+----------------------------------------------------------------------
+### Status:
+enqueued [0,]
+----------------------------------------------------------------------
+### Kind:
+"documentDeletion" [0,]
+----------------------------------------------------------------------
+### Index Tasks:
+doggos [0,]
+----------------------------------------------------------------------
+### Index Mapper:
+
+----------------------------------------------------------------------
+### Canceled By:
+
+----------------------------------------------------------------------
+### Enqueued At:
+[timestamp] [0,]
+----------------------------------------------------------------------
+### Started At:
+----------------------------------------------------------------------
+### Finished At:
+----------------------------------------------------------------------
+### File Store:
+
+----------------------------------------------------------------------
+

index-scheduler/src/snapshots/lib.rs/document_deletion_and_document_addition/registered_the_second_task.snap

@@ -0,0 +1,40 @@
+---
+source: index-scheduler/src/lib.rs
+---
+### Autobatching Enabled = true
+### Processing Tasks:
+[]
+----------------------------------------------------------------------
+### All Tasks:
+0 {uid: 0, status: enqueued, details: { received_document_ids: 2, deleted_documents: None }, kind: DocumentDeletion { index_uid: "doggos", documents_ids: ["1", "2"] }}
+1 {uid: 1, status: enqueued, details: { received_documents: 3, indexed_documents: None }, kind: DocumentAdditionOrUpdate { index_uid: "doggos", primary_key: Some("id"), method: ReplaceDocuments, content_file: 00000000-0000-0000-0000-000000000000, documents_count: 3, allow_index_creation: true }}
+----------------------------------------------------------------------
+### Status:
+enqueued [0,1,]
+----------------------------------------------------------------------
+### Kind:
+"documentAdditionOrUpdate" [1,]
+"documentDeletion" [0,]
+----------------------------------------------------------------------
+### Index Tasks:
+doggos [0,1,]
+----------------------------------------------------------------------
+### Index Mapper:
+
+----------------------------------------------------------------------
+### Canceled By:
+
+----------------------------------------------------------------------
+### Enqueued At:
+[timestamp] [0,]
+[timestamp] [1,]
+----------------------------------------------------------------------
+### Started At:
+----------------------------------------------------------------------
+### Finished At:
+----------------------------------------------------------------------
+### File Store:
+00000000-0000-0000-0000-000000000000
+
+----------------------------------------------------------------------
+

milli/Cargo.toml

@@ -56,6 +56,7 @@ itertools = "0.10.5"
 log = "0.4.17"
 logging_timer = "1.1.0"
 csv = "1.2.1"
+fastrand = "1.9.0"
 
 [dev-dependencies]
 mimalloc = { version = "0.1.29", default-features = false }
@@ -64,12 +65,13 @@ insta = "1.29.0"
 maplit = "1.0.2"
 md5 = "0.7.0"
 rand = {version = "0.8.5", features = ["small_rng"] }
+arbitrary = { version = "1.3.0", features = ["derive"] }
 
 [target.'cfg(fuzzing)'.dev-dependencies]
 fuzzcheck = "0.12.1"
 
 [features]
-all-tokenizations = [ "charabia/default" ]
+all-tokenizations = ["charabia/default"]
 
 # Use POSIX semaphores instead of SysV semaphores in LMDB
 # For more information on this feature, see heed's Cargo.toml

milli/src/documents/mod.rs

@@ -111,7 +111,6 @@ pub enum Error {
     Io(#[from] io::Error),
 }
 
-#[cfg(test)]
 pub fn objects_from_json_value(json: serde_json::Value) -> Vec<crate::Object> {
     let documents = match json {
         object @ serde_json::Value::Object(_) => vec![object],
@@ -141,7 +140,6 @@ macro_rules! documents {
     }};
 }
 
-#[cfg(test)]
 pub fn documents_batch_reader_from_objects(
     objects: impl IntoIterator<Item = Object>,
 ) -> DocumentsBatchReader<std::io::Cursor<Vec<u8>>> {

milli/src/update/index_documents/mod.rs

@@ -198,6 +198,7 @@ where
             let number_of_documents = self.index.number_of_documents(self.wtxn)?;
             return Ok(DocumentAdditionResult { indexed_documents: 0, number_of_documents });
         }
+
         let output = self
             .transform
             .take()
@@ -220,6 +221,7 @@ where
         }
 
         let indexed_documents = output.documents_count as u64;
+
         let number_of_documents = self.execute_raw(output)?;
 
         Ok(DocumentAdditionResult { indexed_documents, number_of_documents })
@@ -236,7 +238,7 @@ where
             primary_key,
             fields_ids_map,
             field_distribution,
-            mut external_documents_ids,
+            new_external_documents_ids,
             new_documents_ids,
             replaced_documents_ids,
             documents_count,
@@ -363,9 +365,6 @@ where
             deletion_builder.delete_documents(&replaced_documents_ids);
             let deleted_documents_result = deletion_builder.execute_inner()?;
             debug!("{} documents actually deleted", deleted_documents_result.deleted_documents);
-            if !deleted_documents_result.soft_deletion_used {
-                external_documents_ids.delete_soft_deleted_documents_ids_from_fsts()?;
-            }
         }
 
         let index_documents_ids = self.index.documents_ids(self.wtxn)?;
@@ -445,6 +444,9 @@ where
         self.index.put_primary_key(self.wtxn, &primary_key)?;
 
         // 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;
@@ -2515,4 +2517,170 @@ mod tests {
         db_snap!(index, word_position_docids, 3, @"74f556b91d161d997a89468b4da1cb8f");
         db_snap!(index, docid_word_positions, 3, @"5287245332627675740b28bd46e1cde1");
     }
+
+    #[test]
+    fn reproduce_the_bug() {
+        /*
+            [milli/examples/fuzz.rs:69] &batches = [
+            Batch(
+                [
+                    AddDoc(
+                        { "id": 1, "doggo": "bernese" }, => internal 0
+                    ),
+                ],
+            ),
+            Batch(
+                [
+                    DeleteDoc(
+                        1, => delete internal 0
+                    ),
+                    AddDoc(
+                        { "id": 0, "catto": "jorts" }, => internal 1
+                    ),
+                ],
+            ),
+            Batch(
+                [
+                    AddDoc(
+                        { "id": 1, "catto": "jorts" }, => internal 2
+                    ),
+                ],
+            ),
+        ]
+        */
+        let mut index = TempIndex::new();
+        index.index_documents_config.deletion_strategy = DeletionStrategy::AlwaysHard;
+
+        // START OF BATCH
+
+        println!("--- ENTERING BATCH 1");
+
+        let mut wtxn = index.write_txn().unwrap();
+
+        let builder = IndexDocuments::new(
+            &mut wtxn,
+            &index,
+            &index.indexer_config,
+            index.index_documents_config.clone(),
+            |_| (),
+            || false,
+        )
+        .unwrap();
+
+        // OP
+
+        let documents = documents!([
+            { "id": 1, "doggo": "bernese" },
+        ]);
+        let (builder, added) = builder.add_documents(documents).unwrap();
+        insta::assert_display_snapshot!(added.unwrap(), @"1");
+
+        // FINISHING
+        let addition = builder.execute().unwrap();
+        insta::assert_debug_snapshot!(addition, @r###"
+        DocumentAdditionResult {
+            indexed_documents: 1,
+            number_of_documents: 1,
+        }
+        "###);
+        wtxn.commit().unwrap();
+
+        db_snap!(index, documents, @r###"
+        {"id":1,"doggo":"bernese"}
+        "###);
+        db_snap!(index, external_documents_ids, @r###"
+        soft:
+        hard:
+        1                        0
+        "###);
+
+        // A first batch of documents has been inserted
+
+        // BATCH 2
+
+        println!("--- ENTERING BATCH 2");
+
+        let mut wtxn = index.write_txn().unwrap();
+
+        let builder = IndexDocuments::new(
+            &mut wtxn,
+            &index,
+            &index.indexer_config,
+            index.index_documents_config.clone(),
+            |_| (),
+            || false,
+        )
+        .unwrap();
+
+        let (builder, removed) = builder.remove_documents(vec![S("1")]).unwrap();
+        insta::assert_display_snapshot!(removed.unwrap(), @"1");
+
+        let documents = documents!([
+            { "id": 0, "catto": "jorts" },
+        ]);
+        let (builder, added) = builder.add_documents(documents).unwrap();
+        insta::assert_display_snapshot!(added.unwrap(), @"1");
+
+        let addition = builder.execute().unwrap();
+        insta::assert_debug_snapshot!(addition, @r###"
+        DocumentAdditionResult {
+            indexed_documents: 1,
+            number_of_documents: 1,
+        }
+        "###);
+        wtxn.commit().unwrap();
+
+        db_snap!(index, documents, @r###"
+        {"id":0,"catto":"jorts"}
+        "###);
+
+        db_snap!(index, external_documents_ids, @r###"
+        soft:
+        hard:
+        0                        1
+        "###);
+
+        db_snap!(index, soft_deleted_documents_ids, @"[]");
+
+        // BATCH 3
+
+        println!("--- ENTERING BATCH 3");
+
+        let mut wtxn = index.write_txn().unwrap();
+
+        let builder = IndexDocuments::new(
+            &mut wtxn,
+            &index,
+            &index.indexer_config,
+            index.index_documents_config.clone(),
+            |_| (),
+            || false,
+        )
+        .unwrap();
+
+        let documents = documents!([
+            { "id": 1, "catto": "jorts" },
+        ]);
+        let (builder, added) = builder.add_documents(documents).unwrap();
+        insta::assert_display_snapshot!(added.unwrap(), @"1");
+
+        let addition = builder.execute().unwrap();
+        insta::assert_debug_snapshot!(addition, @r###"
+        DocumentAdditionResult {
+            indexed_documents: 1,
+            number_of_documents: 2,
+        }
+        "###);
+        wtxn.commit().unwrap();
+
+        db_snap!(index, documents, @r###"
+        {"id":1,"catto":"jorts"}
+        {"id":0,"catto":"jorts"}
+        "###);
+
+        // Ensuring all the returned IDs actually exists
+        let rtxn = index.read_txn().unwrap();
+        let res = index.search(&rtxn).execute().unwrap();
+        index.documents(&rtxn, res.documents_ids).unwrap();
+    }
 }

milli/src/update/index_documents/transform.rs

@@ -21,15 +21,14 @@ use crate::error::{Error, InternalError, UserError};
 use crate::index::{db_name, main_key};
 use crate::update::{AvailableDocumentsIds, ClearDocuments, UpdateIndexingStep};
 use crate::{
-    ExternalDocumentsIds, FieldDistribution, FieldId, FieldIdMapMissingEntry, FieldsIdsMap, Index,
-    Result, BEU32,
+    FieldDistribution, FieldId, FieldIdMapMissingEntry, FieldsIdsMap, Index, Result, BEU32,
 };
 
 pub struct TransformOutput {
     pub primary_key: String,
     pub fields_ids_map: FieldsIdsMap,
     pub field_distribution: FieldDistribution,
-    pub external_documents_ids: ExternalDocumentsIds<'static>,
+    pub new_external_documents_ids: fst::Map<Cow<'static, [u8]>>,
     pub new_documents_ids: RoaringBitmap,
     pub replaced_documents_ids: RoaringBitmap,
     pub documents_count: usize,
@@ -58,8 +57,8 @@ pub struct Transform<'a, 'i> {
     original_sorter: grenad::Sorter<MergeFn>,
     flattened_sorter: grenad::Sorter<MergeFn>,
 
-    replaced_documents_ids: RoaringBitmap,
-    new_documents_ids: RoaringBitmap,
+    pub replaced_documents_ids: RoaringBitmap,
+    pub new_documents_ids: RoaringBitmap,
     // To increase the cache locality and decrease the heap usage we use compact smartstring.
     new_external_documents_ids_builder: FxHashMap<SmartString<smartstring::Compact>, u64>,
     documents_count: usize,
@@ -568,8 +567,6 @@ impl<'a, 'i> Transform<'a, 'i> {
             }))?
             .to_string();
 
-        let mut external_documents_ids = self.index.external_documents_ids(wtxn)?;
-
         // We create a final writer to write the new documents in order from the sorter.
         let mut writer = create_writer(
             self.indexer_settings.chunk_compression_type,
@@ -651,13 +648,14 @@ impl<'a, 'i> Transform<'a, 'i> {
             fst_new_external_documents_ids_builder.insert(key, value)
         })?;
         let new_external_documents_ids = fst_new_external_documents_ids_builder.into_map();
-        external_documents_ids.insert_ids(&new_external_documents_ids)?;
 
         Ok(TransformOutput {
             primary_key,
             fields_ids_map: self.fields_ids_map,
             field_distribution,
-            external_documents_ids: external_documents_ids.into_static(),
+            new_external_documents_ids: new_external_documents_ids
+                .map_data(|c| Cow::Owned(c))
+                .unwrap(),
             new_documents_ids: self.new_documents_ids,
             replaced_documents_ids: self.replaced_documents_ids,
             documents_count: self.documents_count,
@@ -691,7 +689,8 @@ impl<'a, 'i> Transform<'a, 'i> {
         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()?;
-            external_documents_ids
+            // it is safe to get the hard document IDs
+            external_documents_ids.into_static().hard
         };
 
         let documents_ids = self.index.documents_ids(wtxn)?;
@@ -776,7 +775,7 @@ impl<'a, 'i> Transform<'a, 'i> {
             primary_key,
             fields_ids_map: new_fields_ids_map,
             field_distribution,
-            external_documents_ids: new_external_documents_ids.into_static(),
+            new_external_documents_ids,
             new_documents_ids: documents_ids,
             replaced_documents_ids: RoaringBitmap::default(),
             documents_count,