Introduce a dedicated function to write proximity entries in database

milli/src/update/index_documents/typed_chunk.rs

@@ -7,7 +7,7 @@ use bytemuck::allocation::pod_collect_to_vec;
 use charabia::{Language, Script};
 use grenad::{Merger, MergerBuilder};
 use heed::types::Bytes;
-use heed::RwTxn;
+use heed::{BytesDecode, RwTxn};
 use obkv::{KvReader, KvWriter};
 use roaring::RoaringBitmap;
 
@@ -20,13 +20,16 @@ use super::MergeFn;
 use crate::external_documents_ids::{DocumentOperation, DocumentOperationKind};
 use crate::facet::FacetType;
 use crate::index::db_name::DOCUMENTS;
+use crate::proximity::MAX_DISTANCE;
 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, keep_latest_obkv, try_split_array_at,
 };
+use crate::update::settings::InnerIndexSettingsDiff;
 use crate::{
-    lat_lng_to_xyz, DocumentId, FieldId, GeoPoint, Index, InternalError, Result, SerializationError,
+    lat_lng_to_xyz, CboRoaringBitmapCodec, DocumentId, FieldId, GeoPoint, Index, InternalError,
+    Result, SerializationError, U8StrStrCodec,
 };
 
 /// This struct accumulates and group the TypedChunks
@@ -122,7 +125,6 @@ impl TypedChunk {
 /// Return new documents seen.
 #[tracing::instrument(level = "trace", skip_all, target = "indexing::write_db")]
 pub(crate) fn write_typed_chunk_into_index(
-    typed_chunks: Vec<TypedChunk>,
     wtxn: &mut RwTxn,
     index: &Index,
     settings_diff: &InnerIndexSettingsDiff,
@@ -487,6 +489,13 @@ pub(crate) fn write_typed_chunk_into_index(
             }
             let merger = builder.build();
 
+            if settings_diff.only_additional_fields().is_some() {
+                write_proximity_entries_into_database_additional_searchables(
+                    merger,
+                    &index.word_pair_proximity_docids,
+                    wtxn,
+                )?;
+            } else {
                 write_entries_into_database(
                     merger,
                     &index.word_pair_proximity_docids,
@@ -494,6 +503,8 @@ pub(crate) fn write_typed_chunk_into_index(
                     deladd_serialize_add_side,
                     merge_deladd_cbo_roaring_bitmaps_into_cbo_roaring_bitmap,
                 )?;
+            }
+
             is_merged_database = true;
         }
         TypedChunk::FieldIdDocidFacetNumbers(_) => {
@@ -832,3 +843,51 @@ where
     }
     Ok(())
 }
+
+/// Akin to the `write_entries_into_database` function but specialized
+/// for the case when we only index additional searchable fields only.
+#[tracing::instrument(level = "trace", skip_all, target = "indexing::write_db")]
+fn write_proximity_entries_into_database_additional_searchables<R>(
+    merger: Merger<R, MergeFn>,
+    database: &heed::Database<U8StrStrCodec, CboRoaringBitmapCodec>,
+    wtxn: &mut RwTxn,
+) -> Result<()>
+where
+    R: io::Read + io::Seek,
+{
+    let mut iter = merger.into_stream_merger_iter()?;
+    while let Some((key, value)) = iter.next()? {
+        if valid_lmdb_key(key) {
+            let (proximity_to_insert, word1, word2) =
+                U8StrStrCodec::bytes_decode(key).map_err(heed::Error::Decoding)?;
+            let data_to_insert = match KvReaderDelAdd::new(value).get(DelAdd::Addition) {
+                Some(value) => {
+                    CboRoaringBitmapCodec::bytes_decode(value).map_err(heed::Error::Decoding)?
+                }
+                None => continue,
+            };
+
+            let mut data_to_remove = RoaringBitmap::new();
+            for prox in 1..(MAX_DISTANCE as u8) {
+                let key = (prox, word1, word2);
+                let database_value = database.get(wtxn, &key)?.unwrap_or_default();
+                let value = if prox == proximity_to_insert {
+                    // Proximity that should be changed.
+                    // Union values and remove lower proximity data
+                    (&database_value | &data_to_insert) - &data_to_remove
+                } else {
+                    // Remove lower proximity data
+                    &database_value - &data_to_remove
+                };
+
+                // add the current data in data_to_remove for the next proximities
+                data_to_remove |= &value;
+
+                if database_value != value {
+                    database.put(wtxn, &key, &value)?;
+                }
+            }
+        }
+    }
+    Ok(())
+}