diff --git a/milli/src/update/index_documents/extract/mod.rs b/milli/src/update/index_documents/extract/mod.rs
index 341cdc9f9..bf533cfc9 100644
--- a/milli/src/update/index_documents/extract/mod.rs
+++ b/milli/src/update/index_documents/extract/mod.rs
@@ -11,6 +11,7 @@ mod extract_word_position_docids;
 
 use std::fs::File;
 use std::io::BufReader;
+use std::sync::Arc;
 
 use crossbeam_channel::Sender;
 use rayon::prelude::*;
@@ -43,7 +44,7 @@ pub(crate) fn data_from_obkv_documents(
     lmdb_writer_sx: Sender<Result<TypedChunk>>,
     primary_key_id: FieldId,
     geo_fields_ids: Option<(FieldId, FieldId)>,
-    settings_diff: &InnerIndexSettingsDiff,
+    settings_diff: &Arc<InnerIndexSettingsDiff>,
     max_positions_per_attributes: Option<u32>,
 ) -> Result<()> {
     puffin::profile_function!();
@@ -180,7 +181,7 @@ pub(crate) fn data_from_obkv_documents(
 fn run_extraction_task<FE, FS, M>(
     chunk: grenad::Reader<CursorClonableMmap>,
     indexer: GrenadParameters,
-    settings_diff: &InnerIndexSettingsDiff,
+    settings_diff: &Arc<InnerIndexSettingsDiff>,
     lmdb_writer_sx: Sender<Result<TypedChunk>>,
     extract_fn: FE,
     serialize_fn: FS,
@@ -221,7 +222,7 @@ fn send_original_documents_data(
     original_documents_chunk: Result<grenad::Reader<BufReader<File>>>,
     indexer: GrenadParameters,
     lmdb_writer_sx: Sender<Result<TypedChunk>>,
-    settings_diff: &InnerIndexSettingsDiff,
+    settings_diff: &Arc<InnerIndexSettingsDiff>,
 ) -> Result<()> {
     let original_documents_chunk =
         original_documents_chunk.and_then(|c| unsafe { as_cloneable_grenad(&c) })?;
diff --git a/milli/src/update/index_documents/mod.rs b/milli/src/update/index_documents/mod.rs
index 47f1e9f19..070f31c73 100644
--- a/milli/src/update/index_documents/mod.rs
+++ b/milli/src/update/index_documents/mod.rs
@@ -8,6 +8,7 @@ use std::collections::{HashMap, HashSet};
 use std::io::{Read, Seek};
 use std::num::NonZeroU32;
 use std::result::Result as StdResult;
+use std::sync::Arc;
 
 use crossbeam_channel::{Receiver, Sender};
 use grenad::{Merger, MergerBuilder};
@@ -292,6 +293,8 @@ where
         settings_diff.new.recompute_facets(self.wtxn, self.index)?;
         settings_diff.new.recompute_searchables(self.wtxn, self.index)?;
 
+        let settings_diff = Arc::new(settings_diff);
+
         let backup_pool;
         let pool = match self.indexer_config.thread_pool {
             Some(ref pool) => pool,
diff --git a/milli/src/update/index_documents/transform.rs b/milli/src/update/index_documents/transform.rs
index 90c3dbcc0..8a3463e6f 100644
--- a/milli/src/update/index_documents/transform.rs
+++ b/milli/src/update/index_documents/transform.rs
@@ -829,6 +829,9 @@ impl<'a, 'i> Transform<'a, 'i> {
         })
     }
 
+    /// Rebind the field_ids of the provided document to their values
+    /// based on the field_ids_maps difference between the old and the new settings,
+    /// then fill the provided buffers with delta documents using KvWritterDelAdd.
     fn rebind_existing_document(
         old_obkv: KvReader<FieldId>,
         settings_diff: &InnerIndexSettingsDiff,
diff --git a/milli/src/update/settings.rs b/milli/src/update/settings.rs
index 8ded6f03c..1997e966e 100644
--- a/milli/src/update/settings.rs
+++ b/milli/src/update/settings.rs
@@ -1094,7 +1094,6 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
     }
 }
 
-#[derive(Clone)]
 pub struct InnerIndexSettingsDiff {
     pub(crate) old: InnerIndexSettings,
     pub(crate) new: InnerIndexSettings,