diff --git a/milli/src/update/new/indexer/update_by_function.rs b/milli/src/update/new/indexer/update_by_function.rs
index 6bde29b45..6f2914577 100644
--- a/milli/src/update/new/indexer/update_by_function.rs
+++ b/milli/src/update/new/indexer/update_by_function.rs
@@ -204,32 +204,3 @@ fn rhaimap_to_object(map: rhai::Map) -> Object {
     }
     output
 }
-
-fn rhaimap_to_obkv(
-    map: rhai::Map,
-    global_fields_ids_map: &mut GlobalFieldsIdsMap,
-    buffer: &mut Vec<u8>,
-) -> Result<Box<KvReaderFieldId>> {
-    let result: Result<BTreeMap<_, _>> = map
-        .keys()
-        .map(|key| {
-            global_fields_ids_map
-                .id_or_insert(key)
-                .ok_or(UserError::AttributeLimitReached)
-                .map_err(Error::from)
-                .map(|fid| (fid, key))
-        })
-        .collect();
-
-    let ordered_fields = result?;
-    let mut writer = KvWriterFieldId::memory();
-    for (fid, key) in ordered_fields {
-        let value = map.get(key).unwrap();
-        let value = serde_json::to_value(value).unwrap();
-        buffer.clear();
-        serde_json::to_writer(&mut *buffer, &value).unwrap();
-        writer.insert(fid, &buffer)?;
-    }
-
-    Ok(writer.into_boxed())
-}
diff --git a/milli/src/update/new/words_prefix_docids.rs b/milli/src/update/new/words_prefix_docids.rs
index d45f6397e..38c2b1744 100644
--- a/milli/src/update/new/words_prefix_docids.rs
+++ b/milli/src/update/new/words_prefix_docids.rs
@@ -128,9 +128,10 @@ fn delete_prefixes(
 ) -> Result<()> {
     // We remove all the entries that are no more required in this word prefix docids database.
     for prefix in prefixes {
-        let prefix = prefix.as_bytes();
-        if !prefix_database.delete(wtxn, prefix)? {
-            unreachable!("We tried to delete an unknown key")
+        let mut iter = prefix_database.prefix_iter_mut(wtxn, prefix.as_bytes())?;
+        while iter.next().transpose()?.is_some() {
+            // safety: we do not keep a reference on database entries.
+            unsafe { iter.del_current()? };
         }
     }