diff --git a/milli/src/update/facets.rs b/milli/src/update/facets.rs
index a2f17cba3..19684c6ea 100644
--- a/milli/src/update/facets.rs
+++ b/milli/src/update/facets.rs
@@ -15,9 +15,7 @@ use crate::heed_codec::facet::{
     FacetStringLevelZeroValueCodec, FacetStringZeroBoundsValueCodec,
 };
 use crate::heed_codec::CboRoaringBitmapCodec;
-use crate::update::index_documents::{
-    create_writer, write_into_lmdb_database, writer_into_reader, WriteMethod,
-};
+use crate::update::index_documents::{create_writer, write_into_lmdb_database, writer_into_reader};
 use crate::{FieldId, Index, Result};
 
 pub struct Facets<'t, 'u, 'i> {
@@ -120,7 +118,6 @@ impl<'t, 'u, 'i> Facets<'t, 'u, 'i> {
                 *self.index.facet_id_f64_docids.as_polymorph(),
                 facet_number_levels,
                 |_, _| Err(InternalError::IndexingMergingKeys { process: "facet number levels" })?,
-                WriteMethod::GetMergePut,
             )?;
 
             write_into_lmdb_database(
@@ -128,7 +125,6 @@ impl<'t, 'u, 'i> Facets<'t, 'u, 'i> {
                 *self.index.facet_id_string_docids.as_polymorph(),
                 facet_string_levels,
                 |_, _| Err(InternalError::IndexingMergingKeys { process: "facet string levels" })?,
-                WriteMethod::GetMergePut,
             )?;
         }
 
diff --git a/milli/src/update/index_documents/helpers/grenad_helpers.rs b/milli/src/update/index_documents/helpers/grenad_helpers.rs
index 10662892b..eef067122 100644
--- a/milli/src/update/index_documents/helpers/grenad_helpers.rs
+++ b/milli/src/update/index_documents/helpers/grenad_helpers.rs
@@ -9,7 +9,6 @@ use log::debug;
 
 use super::{ClonableMmap, MergeFn};
 use crate::error::InternalError;
-use crate::update::index_documents::WriteMethod;
 use crate::Result;
 
 pub type CursorClonableMmap = io::Cursor<ClonableMmap>;
@@ -169,34 +168,22 @@ pub fn write_into_lmdb_database(
     database: heed::PolyDatabase,
     mut reader: Reader<File>,
     merge: MergeFn,
-    method: WriteMethod,
 ) -> Result<()> {
     debug!("Writing MTBL stores...");
     let before = Instant::now();
 
-    match method {
-        WriteMethod::Append => {
-            let mut out_iter = database.iter_mut::<_, ByteSlice, ByteSlice>(wtxn)?;
-            while let Some((k, v)) = reader.next()? {
+    while let Some((k, v)) = reader.next()? {
+        let mut iter = database.prefix_iter_mut::<_, ByteSlice, ByteSlice>(wtxn, k)?;
+        match iter.next().transpose()? {
+            Some((key, old_val)) if key == k => {
+                let vals = &[Cow::Borrowed(old_val), Cow::Borrowed(v)][..];
+                let val = merge(k, &vals)?;
                 // safety: we don't keep references from inside the LMDB database.
-                unsafe { out_iter.append(k, v)? };
+                unsafe { iter.put_current(k, &val)? };
             }
-        }
-        WriteMethod::GetMergePut => {
-            while let Some((k, v)) = reader.next()? {
-                let mut iter = database.prefix_iter_mut::<_, ByteSlice, ByteSlice>(wtxn, k)?;
-                match iter.next().transpose()? {
-                    Some((key, old_val)) if key == k => {
-                        let vals = &[Cow::Borrowed(old_val), Cow::Borrowed(v)][..];
-                        let val = merge(k, &vals)?;
-                        // safety: we don't keep references from inside the LMDB database.
-                        unsafe { iter.put_current(k, &val)? };
-                    }
-                    _ => {
-                        drop(iter);
-                        database.put::<_, ByteSlice, ByteSlice>(wtxn, k, v)?;
-                    }
-                }
+            _ => {
+                drop(iter);
+                database.put::<_, ByteSlice, ByteSlice>(wtxn, k, v)?;
             }
         }
     }
@@ -210,12 +197,11 @@ pub fn sorter_into_lmdb_database(
     database: heed::PolyDatabase,
     sorter: Sorter<MergeFn>,
     merge: MergeFn,
-    method: WriteMethod,
 ) -> Result<()> {
     debug!("Writing MTBL sorter...");
     let before = Instant::now();
 
-    merger_iter_into_lmdb_database(wtxn, database, sorter.into_merger_iter()?, merge, method)?;
+    merger_iter_into_lmdb_database(wtxn, database, sorter.into_merger_iter()?, merge)?;
 
     debug!("MTBL sorter writen in {:.02?}!", before.elapsed());
     Ok(())
@@ -226,34 +212,22 @@ fn merger_iter_into_lmdb_database<R: io::Read>(
     database: heed::PolyDatabase,
     mut sorter: MergerIter<R, MergeFn>,
     merge: MergeFn,
-    method: WriteMethod,
 ) -> Result<()> {
-    match method {
-        WriteMethod::Append => {
-            let mut out_iter = database.iter_mut::<_, ByteSlice, ByteSlice>(wtxn)?;
-            while let Some((k, v)) = sorter.next()? {
+    while let Some((k, v)) = sorter.next()? {
+        let mut iter = database.prefix_iter_mut::<_, ByteSlice, ByteSlice>(wtxn, k)?;
+        match iter.next().transpose()? {
+            Some((key, old_val)) if key == k => {
+                let vals = vec![Cow::Borrowed(old_val), Cow::Borrowed(v)];
+                let val = merge(k, &vals).map_err(|_| {
+                    // TODO just wrap this error?
+                    InternalError::IndexingMergingKeys { process: "get-put-merge" }
+                })?;
                 // safety: we don't keep references from inside the LMDB database.
-                unsafe { out_iter.append(k, v)? };
+                unsafe { iter.put_current(k, &val)? };
             }
-        }
-        WriteMethod::GetMergePut => {
-            while let Some((k, v)) = sorter.next()? {
-                let mut iter = database.prefix_iter_mut::<_, ByteSlice, ByteSlice>(wtxn, k)?;
-                match iter.next().transpose()? {
-                    Some((key, old_val)) if key == k => {
-                        let vals = vec![Cow::Borrowed(old_val), Cow::Borrowed(v)];
-                        let val = merge(k, &vals).map_err(|_| {
-                            // TODO just wrap this error?
-                            InternalError::IndexingMergingKeys { process: "get-put-merge" }
-                        })?;
-                        // safety: we don't keep references from inside the LMDB database.
-                        unsafe { iter.put_current(k, &val)? };
-                    }
-                    _ => {
-                        drop(iter);
-                        database.put::<_, ByteSlice, ByteSlice>(wtxn, k, v)?;
-                    }
-                }
+            _ => {
+                drop(iter);
+                database.put::<_, ByteSlice, ByteSlice>(wtxn, k, v)?;
             }
         }
     }
diff --git a/milli/src/update/index_documents/mod.rs b/milli/src/update/index_documents/mod.rs
index 7ea5c3816..ee80d8ada 100644
--- a/milli/src/update/index_documents/mod.rs
+++ b/milli/src/update/index_documents/mod.rs
@@ -59,12 +59,6 @@ impl Default for IndexDocumentsMethod {
     }
 }
 
-#[derive(Debug, Copy, Clone)]
-pub enum WriteMethod {
-    Append,
-    GetMergePut,
-}
-
 pub struct IndexDocuments<'t, 'u, 'i, 'a, F> {
     wtxn: &'t mut heed::RwTxn<'i, 'u>,
     index: &'i Index,
diff --git a/milli/src/update/word_prefix_docids.rs b/milli/src/update/word_prefix_docids.rs
index 1e2996c9b..cf50a5b8a 100644
--- a/milli/src/update/word_prefix_docids.rs
+++ b/milli/src/update/word_prefix_docids.rs
@@ -7,7 +7,7 @@ use slice_group_by::GroupBy;
 
 use crate::update::index_documents::{
     create_sorter, fst_stream_into_hashset, fst_stream_into_vec, merge_roaring_bitmaps,
-    sorter_into_lmdb_database, CursorClonableMmap, MergeFn, WriteMethod,
+    sorter_into_lmdb_database, CursorClonableMmap, MergeFn,
 };
 use crate::{Index, Result};
 
@@ -126,7 +126,6 @@ impl<'t, 'u, 'i> WordPrefixDocids<'t, 'u, 'i> {
             *self.index.word_prefix_docids.as_polymorph(),
             prefix_docids_sorter,
             merge_roaring_bitmaps,
-            WriteMethod::GetMergePut,
         )?;
 
         Ok(())
diff --git a/milli/src/update/word_prefix_pair_proximity_docids.rs b/milli/src/update/word_prefix_pair_proximity_docids.rs
index f846e8d9e..5b025e4fc 100644
--- a/milli/src/update/word_prefix_pair_proximity_docids.rs
+++ b/milli/src/update/word_prefix_pair_proximity_docids.rs
@@ -8,7 +8,7 @@ use slice_group_by::GroupBy;
 
 use crate::update::index_documents::{
     create_sorter, fst_stream_into_hashset, fst_stream_into_vec, merge_cbo_roaring_bitmaps,
-    sorter_into_lmdb_database, CursorClonableMmap, MergeFn, WriteMethod,
+    sorter_into_lmdb_database, CursorClonableMmap, MergeFn,
 };
 use crate::{Index, Result, StrStrU8Codec};
 
@@ -192,7 +192,6 @@ impl<'t, 'u, 'i> WordPrefixPairProximityDocids<'t, 'u, 'i> {
             *self.index.word_prefix_pair_proximity_docids.as_polymorph(),
             word_prefix_pair_proximity_docids_sorter,
             merge_cbo_roaring_bitmaps,
-            WriteMethod::GetMergePut,
         )?;
 
         Ok(())
diff --git a/milli/src/update/words_prefix_position_docids.rs b/milli/src/update/words_prefix_position_docids.rs
index b1b8273ef..178684cf0 100644
--- a/milli/src/update/words_prefix_position_docids.rs
+++ b/milli/src/update/words_prefix_position_docids.rs
@@ -14,7 +14,7 @@ use crate::heed_codec::StrBEU32Codec;
 use crate::index::main_key::WORDS_PREFIXES_FST_KEY;
 use crate::update::index_documents::{
     create_sorter, fst_stream_into_hashset, fst_stream_into_vec, merge_cbo_roaring_bitmaps,
-    sorter_into_lmdb_database, CursorClonableMmap, MergeFn, WriteMethod,
+    sorter_into_lmdb_database, CursorClonableMmap, MergeFn,
 };
 use crate::{Index, Result};
 
@@ -170,7 +170,6 @@ impl<'t, 'u, 'i> WordPrefixPositionDocids<'t, 'u, 'i> {
             *self.index.word_prefix_position_docids.as_polymorph(),
             prefix_position_docids_sorter,
             merge_cbo_roaring_bitmaps,
-            WriteMethod::GetMergePut,
         )?;
 
         Ok(())