diff --git a/Cargo.lock b/Cargo.lock
index b3991d130..d8cd12cc2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2703,6 +2703,7 @@ dependencies = [
  "logging_timer",
  "maplit",
  "md5",
+ "meili-snap",
  "memmap2",
  "mimalloc",
  "obkv",
diff --git a/milli/Cargo.toml b/milli/Cargo.toml
index b19b40e85..68bc2d2b5 100644
--- a/milli/Cargo.toml
+++ b/milli/Cargo.toml
@@ -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]
diff --git a/milli/src/search/new/tests/sort.rs b/milli/src/search/new/tests/sort.rs
index aa6aa971f..8fdf52d44 100644
--- a/milli/src/search/new/tests/sort.rs
+++ b/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;
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 643d16354..6aa66c92a 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
@@ -5,11 +5,11 @@ 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::{
@@ -43,7 +43,7 @@ pub fn extract_docid_word_positions<R: io::Read + io::Seek>(
     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,
@@ -156,6 +156,7 @@ 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();
                 for (index, token) in tokens {
                     // if a language has been detected for the token, we update the counter.
                     if let Some(language) = token.language {
@@ -169,17 +170,17 @@ fn extract_tokens_from_document(
                     }
                     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
                             .try_into()
                             .map_err(|_| SerializationError::InvalidNumberSerialization)?;
-                        let position = absolute_from_relative_position(field_id, position);
-                        docid_word_positions_sorter
-                            .insert(&buffers.key_buffer, position.to_ne_bytes())?;
+                        writer.insert(position, token.as_bytes())?;
                     }
                 }
+
+                let positions = writer.into_inner()?;
+                buffers.key_buffer.truncate(mem::size_of::<u32>());
+                buffers.key_buffer.extend_from_slice(&field_id.to_be_bytes());
+                docid_word_positions_sorter.insert(&buffers.key_buffer, positions)?;
             }
         }
     }
diff --git a/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs b/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs
index 92564b4cd..289a744da 100644
--- a/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs
@@ -1,16 +1,17 @@
-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,
-    try_split_array_at, GrenadParameters, MergeFn,
+    create_sorter, merge_cbo_roaring_bitmaps, 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, FieldId, Result};
+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.
@@ -35,63 +36,21 @@ pub fn extract_fid_word_count_docids<R: io::Read + io::Seek>(
         max_memory,
     );
 
-    // This map is assumed to not consume a lot of memory.
-    let mut document_fid_wordcount = HashMap::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, _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);
-        if curr_document_id != document_id {
-            drain_document_fid_wordcount_into_sorter(
-                &mut fid_word_count_docids_sorter,
-                &mut document_fid_wordcount,
-                curr_document_id,
-            )?;
-            current_document_id = Some(document_id);
-        }
-
-        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 {
+        let word_count = KvReaderU16::new(&value).iter().take(MAX_COUNTED_WORDS + 1).count();
+        if word_count <= MAX_COUNTED_WORDS {
             key_buffer.clear();
-            key_buffer.extend_from_slice(&fid.to_be_bytes());
-            key_buffer.push(count as u8);
-
+            key_buffer.extend_from_slice(fid_bytes);
+            key_buffer.push(word_count as u8);
             fid_word_count_docids_sorter.insert(&key_buffer, document_id.to_ne_bytes())?;
         }
     }
 
-    Ok(())
+    sorter_into_reader(fid_word_count_docids_sorter, indexer)
 }
diff --git a/milli/src/update/index_documents/extract/extract_word_docids.rs b/milli/src/update/index_documents/extract/extract_word_docids.rs
index f211f7023..8b93ea23c 100644
--- a/milli/src/update/index_documents/extract/extract_word_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_docids.rs
@@ -1,18 +1,19 @@
-use std::collections::HashSet;
+use std::collections::{BTreeSet, HashSet};
 use std::fs::File;
 use std::io::{self, BufReader};
 use std::iter::FromIterator;
 
+use obkv::KvReaderU16;
 use roaring::RoaringBitmap;
 
 use super::helpers::{
-    create_sorter, merge_roaring_bitmaps, serialize_roaring_bitmap, sorter_into_reader,
-    try_split_array_at, GrenadParameters,
+    create_sorter, merge_cbo_roaring_bitmaps, merge_roaring_bitmaps, serialize_roaring_bitmap,
+    sorter_into_reader, try_split_array_at, GrenadParameters,
 };
 use crate::error::SerializationError;
 use crate::index::db_name::DOCID_WORD_POSITIONS;
-use crate::update::index_documents::helpers::read_u32_ne_bytes;
-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.
 ///
@@ -26,7 +27,11 @@ 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();
@@ -37,7 +42,7 @@ pub fn extract_word_docids<R: io::Read + io::Seek>(
         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 exact_word_docids_sorter = create_sorter(
@@ -46,45 +51,116 @@ pub fn extract_word_docids<R: io::Read + io::Seek>(
         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 word_fid_docids_sorter = create_sorter(
+        grenad::SortAlgorithm::Unstable,
+        merge_roaring_bitmaps,
+        indexer.chunk_compression_type,
+        indexer.chunk_compression_level,
+        indexer.max_nb_chunks,
+        max_memory.map(|x| x / 3),
+    );
+
+    let mut current_document_id = None;
+    let mut fid = 0;
+    let mut key_buffer = Vec::new();
     let mut value_buffer = Vec::new();
+    let mut words = BTreeSet::new();
+    let mut exact_words = BTreeSet::new();
     let mut cursor = docid_word_positions.into_cursor()?;
-    while let Some((key, positions)) = cursor.move_on_next()? {
-        let (document_id_bytes, word_bytes) = try_split_array_at(key)
+    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(key)
             .ok_or(SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
         let document_id = u32::from_be_bytes(document_id_bytes);
+        fid = u16::from_be_bytes(fid_bytes);
 
-        let bitmap = RoaringBitmap::from_iter(Some(document_id));
-        serialize_roaring_bitmap(&bitmap, &mut value_buffer)?;
+        // drain the btreemaps when we change document.
+        if current_document_id.map_or(false, |id| id != document_id) {
+            words_into_sorters(
+                document_id,
+                fid,
+                &mut key_buffer,
+                &mut value_buffer,
+                &mut exact_words,
+                &mut words,
+                &mut exact_word_docids_sorter,
+                &mut word_docids_sorter,
+                &mut word_fid_docids_sorter,
+            )?;
+        }
 
-        // 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)?;
+        current_document_id = Some(document_id);
+
+        // every words contained in an attribute set to exact must be pushed in the exact_words list.
+        if exact_attributes.contains(&fid) {
+            for (_pos, word) in KvReaderU16::new(&value).iter() {
+                exact_words.insert(word.to_vec());
+            }
         } else {
-            let mut added_to_exact = false;
-            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;
-                }
+            for (_pos, word) in KvReaderU16::new(&value).iter() {
+                words.insert(word.to_vec());
             }
         }
     }
 
+    // We must make sure that don't lose the current document field id
+    if let Some(document_id) = current_document_id {
+        words_into_sorters(
+            document_id,
+            fid,
+            &mut key_buffer,
+            &mut value_buffer,
+            &mut exact_words,
+            &mut words,
+            &mut exact_word_docids_sorter,
+            &mut word_docids_sorter,
+            &mut word_fid_docids_sorter,
+        )?;
+    }
+
     Ok((
         sorter_into_reader(word_docids_sorter, indexer)?,
         sorter_into_reader(exact_word_docids_sorter, indexer)?,
+        sorter_into_reader(word_fid_docids_sorter, indexer)?,
     ))
 }
+
+fn words_into_sorters(
+    document_id: DocumentId,
+    fid: FieldId,
+    key_buffer: &mut Vec<u8>,
+    value_buffer: &mut Vec<u8>,
+    exact_words: &mut BTreeSet<Vec<u8>>,
+    words: &mut BTreeSet<Vec<u8>>,
+    exact_word_docids_sorter: &mut grenad::Sorter<MergeFn>,
+    word_docids_sorter: &mut grenad::Sorter<MergeFn>,
+    word_fid_docids_sorter: &mut grenad::Sorter<MergeFn>,
+) -> Result<()> {
+    puffin::profile_function!();
+    let bitmap = RoaringBitmap::from_iter(Some(document_id));
+    serialize_roaring_bitmap(&bitmap, value_buffer)?;
+    for word_bytes in exact_words.iter() {
+        exact_word_docids_sorter.insert(word_bytes, &mut *value_buffer)?;
+    }
+
+    for word_bytes in words.iter() {
+        word_docids_sorter.insert(word_bytes, &value_buffer)?;
+    }
+
+    for word_bytes in (&*words | &*exact_words).iter() {
+        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(word_bytes, &value_buffer)?;
+    }
+
+    exact_words.clear();
+    words.clear();
+
+    Ok(())
+}
diff --git a/milli/src/update/index_documents/extract/extract_word_fid_docids.rs b/milli/src/update/index_documents/extract/extract_word_fid_docids.rs
index 09f571038..dd4d42431 100644
--- a/milli/src/update/index_documents/extract/extract_word_fid_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_fid_docids.rs
@@ -17,6 +17,8 @@ pub fn extract_word_fid_docids<R: io::Read + io::Seek>(
 ) -> Result<grenad::Reader<BufReader<File>>> {
     puffin::profile_function!();
 
+    todo!("remove me");
+
     let max_memory = indexer.max_memory_by_thread();
 
     let mut word_fid_docids_sorter = create_sorter(
diff --git a/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs b/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs
index 9ddd5ff4c..41604ff4a 100644
--- a/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs
@@ -1,12 +1,14 @@
 use std::cmp::Ordering;
-use std::collections::{BinaryHeap, HashMap};
+use std::collections::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,
-    try_split_array_at, GrenadParameters, MergeFn,
+    create_sorter, merge_cbo_roaring_bitmaps, sorter_into_reader, try_split_array_at,
+    GrenadParameters, MergeFn,
 };
 use crate::error::SerializationError;
 use crate::index::db_name::DOCID_WORD_POSITIONS;
@@ -35,44 +37,59 @@ pub fn extract_word_pair_proximity_docids<R: io::Read + io::Seek>(
         max_memory.map(|m| m / 2),
     );
 
-    // This map is assumed to not consume a lot of memory.
-    let mut document_word_positions_heap = BinaryHeap::new();
+    let mut word_positions: Vec<(String, u16)> = Vec::with_capacity(MAX_DISTANCE as usize);
+    let mut word_pair_proximity = HashMap::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 curr_document_id != document_id {
-            let document_word_positions_heap = mem::take(&mut document_word_positions_heap);
-            document_word_positions_into_sorter(
-                curr_document_id,
-                document_word_positions_heap,
-                &mut word_pair_proximity_docids_sorter,
-            )?;
-            current_document_id = Some(document_id);
-        }
+        for (position, word) in KvReaderU16::new(&value).iter() {
+            // if we change document, we fill the sorter
+            if current_document_id.map_or(false, |id| id != document_id) {
+                while !word_positions.is_empty() {
+                    word_positions_into_word_pair_proximity(
+                        &mut word_positions,
+                        &mut word_pair_proximity,
+                    )?;
+                }
 
-        let word = word.to_string();
-        let mut positions: Vec<_> = read_u32_ne_bytes(value).collect();
-        positions.sort_unstable();
-        let mut iter = positions.into_iter();
-        if let Some(position) = iter.next() {
-            document_word_positions_heap.push(PeekedWordPosition { word, position, iter });
+                document_word_positions_into_sorter(
+                    document_id,
+                    &word_pair_proximity,
+                    &mut word_pair_proximity_docids_sorter,
+                )?;
+                word_pair_proximity.clear();
+                word_positions.clear();
+            }
+
+            // drain the proximity window until the head word is considered close to the word we are inserting.
+            while word_positions.get(0).map_or(false, |(_w, p)| {
+                positions_proximity(*p as u32, position as u32) > MAX_DISTANCE
+            }) {
+                word_positions_into_word_pair_proximity(
+                    &mut word_positions,
+                    &mut word_pair_proximity,
+                )?;
+            }
+
+            // insert the new word.
+            let word = std::str::from_utf8(word)?;
+            word_positions.push((word.to_string(), position));
         }
     }
 
     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.
-        let document_word_positions_heap = mem::take(&mut document_word_positions_heap);
+        while !word_positions.is_empty() {
+            word_positions_into_word_pair_proximity(&mut word_positions, &mut word_pair_proximity)?;
+        }
+
         document_word_positions_into_sorter(
             document_id,
-            document_word_positions_heap,
+            &word_pair_proximity,
             &mut word_pair_proximity_docids_sorter,
         )?;
     }
@@ -86,64 +103,13 @@ 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>>>,
+    word_pair_proximity: &HashMap<(String, String), u8>,
     word_pair_proximity_docids_sorter: &mut grenad::Sorter<MergeFn>,
 ) -> Result<()> {
-    let mut word_pair_proximity = HashMap::new();
-    let mut ordered_peeked_word_positions = Vec::new();
-    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 key_buffer = Vec::new();
     for ((w1, w2), prox) in word_pair_proximity {
         key_buffer.clear();
-        key_buffer.push(prox as u8);
+        key_buffer.push(*prox as u8);
         key_buffer.extend_from_slice(w1.as_bytes());
         key_buffer.push(0);
         key_buffer.extend_from_slice(w2.as_bytes());
@@ -154,6 +120,23 @@ fn document_word_positions_into_sorter(
     Ok(())
 }
 
+fn word_positions_into_word_pair_proximity(
+    word_positions: &mut Vec<(String, u16)>,
+    word_pair_proximity: &mut HashMap<(String, String), u8>,
+) -> Result<()> {
+    let (head_word, head_position) = word_positions.remove(0);
+    for (word, position) in word_positions.iter() {
+        let prox = positions_proximity(head_position as u32, *position as u32) as u8;
+        word_pair_proximity
+            .entry((head_word.clone(), word.clone()))
+            .and_modify(|p| {
+                *p = cmp::min(*p, prox);
+            })
+            .or_insert(prox);
+    }
+    Ok(())
+}
+
 struct PeekedWordPosition<I> {
     word: String,
     position: u32,
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 94139ddf8..db2f6217f 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
@@ -1,13 +1,15 @@
 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,
-    try_split_array_at, GrenadParameters,
+    create_sorter, merge_cbo_roaring_bitmaps, sorter_into_reader, try_split_array_at,
+    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::{bucketed_position, DocumentId, Result};
 
 /// Extracts the word positions and the documents ids where this word appear.
 ///
@@ -34,15 +36,14 @@ pub fn extract_word_position_docids<R: io::Read + io::Seek>(
     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) {
+        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) = relative_from_absolute_position(position);
             let position = bucketed_position(position);
             key_buffer.extend_from_slice(&position.to_be_bytes());
             word_position_docids_sorter.insert(&key_buffer, document_id.to_ne_bytes())?;
diff --git a/milli/src/update/index_documents/extract/mod.rs b/milli/src/update/index_documents/extract/mod.rs
index f44eac8f5..a6cc04111 100644
--- a/milli/src/update/index_documents/extract/mod.rs
+++ b/milli/src/update/index_documents/extract/mod.rs
@@ -176,16 +176,23 @@ pub(crate) fn data_from_obkv_documents(
     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,
-        |(word_docids_reader, exact_word_docids_reader)| TypedChunk::WordDocids {
-            word_docids_reader,
-            exact_word_docids_reader,
+        |(word_docids_reader, exact_word_docids_reader, word_fid_docids_reader)| {
+            TypedChunk::WordDocids {
+                word_docids_reader,
+                exact_word_docids_reader,
+                word_fid_docids_reader,
+            }
         },
         "word-docids",
     );
@@ -199,15 +206,15 @@ pub(crate) fn data_from_obkv_documents(
         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_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,
diff --git a/milli/src/update/index_documents/helpers/grenad_helpers.rs b/milli/src/update/index_documents/helpers/grenad_helpers.rs
index 582bf2a5b..6c3a81a0e 100644
--- a/milli/src/update/index_documents/helpers/grenad_helpers.rs
+++ b/milli/src/update/index_documents/helpers/grenad_helpers.rs
@@ -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> {
diff --git a/milli/src/update/index_documents/mod.rs b/milli/src/update/index_documents/mod.rs
index 52aa1113e..58219f28c 100644
--- a/milli/src/update/index_documents/mod.rs
+++ b/milli/src/update/index_documents/mod.rs
@@ -406,13 +406,23 @@ where
             }
 
             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::WordDocids {
+                        word_docids_reader,
+                        exact_word_docids_reader,
+                        word_fid_docids_reader,
+                    }
                 }
                 TypedChunk::WordPairProximityDocids(chunk) => {
                     let cloneable_chunk = unsafe { as_cloneable_grenad(&chunk)? };
diff --git a/milli/src/update/index_documents/typed_chunk.rs b/milli/src/update/index_documents/typed_chunk.rs
index 5895a69c5..d57484cab 100644
--- a/milli/src/update/index_documents/typed_chunk.rs
+++ b/milli/src/update/index_documents/typed_chunk.rs
@@ -32,6 +32,7 @@ pub(crate) enum TypedChunk {
     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>>),
@@ -64,10 +65,15 @@ impl TypedChunk {
             TypedChunk::NewDocumentsIds(grenad) => {
                 format!("NewDocumentsIds {{ number_of_entries: {} }}", grenad.len())
             }
-            TypedChunk::WordDocids { word_docids_reader, exact_word_docids_reader } => format!(
-                "WordDocids {{ word_docids_reader: {}, exact_word_docids_reader: {} }}",
+            TypedChunk::WordDocids {
+                word_docids_reader,
+                exact_word_docids_reader,
+                word_fid_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())
@@ -138,7 +144,11 @@ pub(crate) fn write_typed_chunk_into_index(
         TypedChunk::NewDocumentsIds(documents_ids) => {
             return Ok((documents_ids, is_merged_database))
         }
-        TypedChunk::WordDocids { 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(),
@@ -159,6 +169,16 @@ pub(crate) fn write_typed_chunk_into_index(
                 merge_roaring_bitmaps,
             )?;
 
+            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,
+                |value, _buffer| Ok(value),
+                merge_cbo_roaring_bitmaps,
+            )?;
+
             // create fst from word docids
             let fst = merge_word_docids_reader_into_fst(word_docids_iter, exact_word_docids_iter)?;
             let db_fst = index.words_fst(wtxn)?;