diff --git a/milli/src/update/index_documents/extract/extract_docid_word_positions.rs b/milli/src/update/index_documents/extract/extract_docid_word_positions.rs
index f99fbbc4e..ff25caa1a 100644
--- a/milli/src/update/index_documents/extract/extract_docid_word_positions.rs
+++ b/milli/src/update/index_documents/extract/extract_docid_word_positions.rs
@@ -155,7 +155,8 @@ fn extract_tokens_from_document(
                 let tokens = process_tokens(tokenizer.tokenize(field))
                     .take_while(|(p, _)| (*p as u32) < max_positions_per_attributes);
 
-                let mut writer = KvWriterU16::memory();
+                buffers.obkv_buffer.clear();
+                let mut writer = KvWriterU16::new(&mut buffers.obkv_buffer);
                 for (index, token) in tokens {
                     // if a language has been detected for the token, we update the counter.
                     if let Some(language) = token.language {
@@ -293,4 +294,6 @@ struct Buffers {
     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>,
 }
diff --git a/milli/src/update/index_documents/extract/extract_word_position_docids.rs b/milli/src/update/index_documents/extract/extract_word_position_docids.rs
index 0e2aa2021..638052b37 100644
--- a/milli/src/update/index_documents/extract/extract_word_position_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_position_docids.rs
@@ -1,3 +1,4 @@
+use std::collections::HashSet;
 use std::fs::File;
 use std::io;
 
@@ -33,18 +34,39 @@ pub fn extract_word_position_docids<R: io::Read + io::Seek>(
         max_memory,
     );
 
+    let mut word_positions: HashSet<(u16, Vec<u8>)> = HashSet::new();
+    let mut current_document_id = 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, fid_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);
 
+        if current_document_id.map_or(false, |id| document_id != id) {
+            for (position, word_bytes) in word_positions.iter() {
+                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, document_id.to_ne_bytes())?;
+            }
+            word_positions.clear();
+        }
+
+        current_document_id = Some(document_id);
+
         for (position, word_bytes) in KvReaderU16::new(&value).iter() {
-            key_buffer.clear();
-            key_buffer.extend_from_slice(word_bytes);
-            key_buffer.push(0);
             let position = bucketed_position(position);
+            word_positions.insert((position, word_bytes.to_vec()));
+        }
+    }
+
+    if let Some(document_id) = current_document_id {
+        for (position, word_bytes) in word_positions {
+            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, document_id.to_ne_bytes())?;
         }