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 b1a6bb5a6..6cf7b3167 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
@@ -34,6 +34,7 @@ pub fn extract_docid_word_positions<R: io::Read + io::Seek>(
     let max_positions_per_attributes = max_positions_per_attributes
         .map_or(MAX_POSITION_PER_ATTRIBUTE, |max| max.min(MAX_POSITION_PER_ATTRIBUTE));
     let max_memory = indexer.max_memory_by_thread();
+    let force_reindexing = settings_diff.reindex_searchable();
 
     // initialize destination values.
     let mut documents_ids = RoaringBitmap::new();
@@ -54,12 +55,15 @@ pub fn extract_docid_word_positions<R: io::Read + io::Seek>(
     let mut value_buffer = Vec::new();
 
     // initialize tokenizer.
-    // TODO: Fix ugly allocation
+    /// TODO: Fix ugly allocation
     let old_stop_words = settings_diff.old.stop_words.as_ref();
-    let old_separators: Option<Vec<_>> =
-        settings_diff.old.allowed_separators.map(|s| s.iter().map(String::as_str).collect());
+    let old_separators: Option<Vec<_>> = settings_diff
+        .old
+        .allowed_separators
+        .as_ref()
+        .map(|s| s.iter().map(String::as_str).collect());
     let old_dictionary: Option<Vec<_>> =
-        settings_diff.old.dictionary.map(|s| s.iter().map(String::as_str).collect());
+        settings_diff.old.dictionary.as_ref().map(|s| s.iter().map(String::as_str).collect());
     let mut del_builder = tokenizer_builder(
         old_stop_words,
         old_separators.as_deref(),
@@ -68,12 +72,15 @@ pub fn extract_docid_word_positions<R: io::Read + io::Seek>(
     );
     let del_tokenizer = del_builder.build();
 
-    // TODO: Fix ugly allocation
+    /// TODO: Fix ugly allocation
     let new_stop_words = settings_diff.new.stop_words.as_ref();
-    let new_separators: Option<Vec<_>> =
-        settings_diff.new.allowed_separators.map(|s| s.iter().map(String::as_str).collect());
+    let new_separators: Option<Vec<_>> = settings_diff
+        .new
+        .allowed_separators
+        .as_ref()
+        .map(|s| s.iter().map(String::as_str).collect());
     let new_dictionary: Option<Vec<_>> =
-        settings_diff.new.dictionary.map(|s| s.iter().map(String::as_str).collect());
+        settings_diff.new.dictionary.as_ref().map(|s| s.iter().map(String::as_str).collect());
     let mut add_builder = tokenizer_builder(
         new_stop_words,
         new_separators.as_deref(),
@@ -92,10 +99,7 @@ pub fn extract_docid_word_positions<R: io::Read + io::Seek>(
         let obkv = KvReader::<FieldId>::new(value);
 
         // if the searchable fields didn't change, skip the searchable indexing for this document.
-        if !searchable_fields_changed(
-            &KvReader::<FieldId>::new(value),
-            &settings_diff.new.searchable_fields_ids,
-        ) {
+        if !force_reindexing && !searchable_fields_changed(&obkv, settings_diff) {
             continue;
         }
 
@@ -180,8 +184,9 @@ pub fn extract_docid_word_positions<R: io::Read + io::Seek>(
 /// Check if any searchable fields of a document changed.
 fn searchable_fields_changed(
     obkv: &KvReader<FieldId>,
-    searchable_fields: &Option<Vec<FieldId>>,
+    settings_diff: &InnerIndexSettingsDiff,
 ) -> bool {
+    let searchable_fields = &settings_diff.new.searchable_fields_ids;
     for (field_id, field_bytes) in obkv.iter() {
         if searchable_fields.as_ref().map_or(true, |sf| sf.contains(&field_id)) {
             let del_add = KvReaderDelAdd::new(field_bytes);
@@ -262,12 +267,14 @@ fn lang_safe_tokens_from_document<'a>(
         // then we don't rerun the extraction.
         if !script_language.is_empty() {
             // build a new temporary tokenizer including the allow list.
-            // TODO: Fix ugly allocation
+            /// TODO: Fix ugly allocation
             let stop_words = settings.stop_words.as_ref();
-            let separators: Option<Vec<_>> =
-                settings.allowed_separators.map(|s| s.iter().map(String::as_str).collect());
+            let separators: Option<Vec<_>> = settings
+                .allowed_separators
+                .as_ref()
+                .map(|s| s.iter().map(String::as_str).collect());
             let dictionary: Option<Vec<_>> =
-                settings.dictionary.map(|s| s.iter().map(String::as_str).collect());
+                settings.dictionary.as_ref().map(|s| s.iter().map(String::as_str).collect());
             let mut builder =
                 tokenizer_builder(stop_words, separators.as_deref(), dictionary.as_deref(), None);
             let tokenizer = builder.build();
diff --git a/milli/src/update/index_documents/extract/extract_vector_points.rs b/milli/src/update/index_documents/extract/extract_vector_points.rs
index 40b32bf9c..fc79a861f 100644
--- a/milli/src/update/index_documents/extract/extract_vector_points.rs
+++ b/milli/src/update/index_documents/extract/extract_vector_points.rs
@@ -17,8 +17,9 @@ use crate::error::UserError;
 use crate::prompt::Prompt;
 use crate::update::del_add::{DelAdd, KvReaderDelAdd, KvWriterDelAdd};
 use crate::update::index_documents::helpers::try_split_at;
+use crate::update::settings::InnerIndexSettingsDiff;
 use crate::vector::Embedder;
-use crate::{DocumentId, FieldsIdsMap, InternalError, Result, VectorOrArrayOfVectors};
+use crate::{DocumentId, InternalError, Result, VectorOrArrayOfVectors};
 
 /// The length of the elements that are always in the buffer when inserting new values.
 const TRUNCATE_SIZE: usize = size_of::<DocumentId>();
@@ -71,12 +72,15 @@ impl VectorStateDelta {
 pub fn extract_vector_points<R: io::Read + io::Seek>(
     obkv_documents: grenad::Reader<R>,
     indexer: GrenadParameters,
-    field_id_map: &FieldsIdsMap,
+    settings_diff: &InnerIndexSettingsDiff,
     prompt: &Prompt,
     embedder_name: &str,
 ) -> Result<ExtractedVectorPoints> {
     puffin::profile_function!();
 
+    let old_fields_ids_map = &settings_diff.old.fields_ids_map;
+    let new_fields_ids_map = &settings_diff.new.fields_ids_map;
+
     // (docid, _index) -> KvWriterDelAdd -> Vector
     let mut manual_vectors_writer = create_writer(
         indexer.chunk_compression_type,
@@ -98,8 +102,6 @@ pub fn extract_vector_points<R: io::Read + io::Seek>(
         tempfile::tempfile()?,
     );
 
-    let vectors_fid = field_id_map.id("_vectors");
-
     let mut key_buffer = Vec::new();
     let mut cursor = obkv_documents.into_cursor()?;
     while let Some((key, value)) = cursor.move_on_next()? {
@@ -116,15 +118,29 @@ pub fn extract_vector_points<R: io::Read + io::Seek>(
         // lazily get it when needed
         let document_id = || -> Value { from_utf8(external_id_bytes).unwrap().into() };
 
-        let vectors_field = vectors_fid
-            .and_then(|vectors_fid| obkv.get(vectors_fid))
-            .map(KvReaderDelAdd::new)
-            .map(|obkv| to_vector_maps(obkv, document_id))
-            .transpose()?;
+        // the vector field id may have changed
+        let old_vectors_fid = old_fields_ids_map.id("_vectors");
+        // filter the old vector fid if the settings has been changed forcing reindexing.
+        let old_vectors_fid = old_vectors_fid.filter(|_| !settings_diff.reindex_vectors());
 
-        let (del_map, add_map) = vectors_field.unzip();
-        let del_map = del_map.flatten();
-        let add_map = add_map.flatten();
+        let new_vectors_fid = new_fields_ids_map.id("_vectors");
+        let vectors_field = {
+            let del = old_vectors_fid
+                .and_then(|vectors_fid| obkv.get(vectors_fid))
+                .map(KvReaderDelAdd::new)
+                .map(|obkv| to_vector_map(obkv, DelAdd::Deletion, &document_id))
+                .transpose()?
+                .flatten();
+            let add = new_vectors_fid
+                .and_then(|vectors_fid| obkv.get(vectors_fid))
+                .map(KvReaderDelAdd::new)
+                .map(|obkv| to_vector_map(obkv, DelAdd::Addition, &document_id))
+                .transpose()?
+                .flatten();
+            (del, add)
+        };
+
+        let (del_map, add_map) = vectors_field;
 
         let del_value = del_map.and_then(|mut map| map.remove(embedder_name));
         let add_value = add_map.and_then(|mut map| map.remove(embedder_name));
@@ -155,7 +171,7 @@ pub fn extract_vector_points<R: io::Read + io::Seek>(
                     VectorStateDelta::NowGenerated(prompt.render(
                         obkv,
                         DelAdd::Addition,
-                        field_id_map,
+                        &new_fields_ids_map,
                     )?)
                 } else {
                     VectorStateDelta::NowRemoved
@@ -182,9 +198,10 @@ pub fn extract_vector_points<R: io::Read + io::Seek>(
 
                 if document_is_kept {
                     // Don't give up if the old prompt was failing
-                    let old_prompt =
-                        prompt.render(obkv, DelAdd::Deletion, field_id_map).unwrap_or_default();
-                    let new_prompt = prompt.render(obkv, DelAdd::Addition, field_id_map)?;
+                    let old_prompt = prompt
+                        .render(obkv, DelAdd::Deletion, &old_fields_ids_map)
+                        .unwrap_or_default();
+                    let new_prompt = prompt.render(obkv, DelAdd::Addition, &new_fields_ids_map)?;
                     if old_prompt != new_prompt {
                         tracing::trace!(
                             "🚀 Changing prompt from\n{old_prompt}\n===to===\n{new_prompt}"
@@ -220,15 +237,6 @@ pub fn extract_vector_points<R: io::Read + io::Seek>(
     })
 }
 
-fn to_vector_maps(
-    obkv: KvReaderDelAdd,
-    document_id: impl Fn() -> Value,
-) -> Result<(Option<serde_json::Map<String, Value>>, Option<serde_json::Map<String, Value>>)> {
-    let del = to_vector_map(obkv, DelAdd::Deletion, &document_id)?;
-    let add = to_vector_map(obkv, DelAdd::Addition, &document_id)?;
-    Ok((del, add))
-}
-
 fn to_vector_map(
     obkv: KvReaderDelAdd,
     side: DelAdd,
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 2b1f02326..2be41bb86 100644
--- a/milli/src/update/index_documents/extract/extract_word_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_docids.rs
@@ -121,16 +121,16 @@ pub fn extract_word_docids<R: io::Read + io::Seek>(
         let (w, fid) = StrBEU16Codec::bytes_decode(key)
             .map_err(|_| SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
 
-        if let Some(word) = word {
-            if word.as_str() != w {
-                docids_into_writers(&word, &deletions, &additions, &mut word_docids_writer);
+        if let Some(current) = word.as_ref() {
+            if current != w {
+                docids_into_writers(&current, &deletions, &additions, &mut word_docids_writer)?;
                 docids_into_writers(
-                    &word,
+                    &current,
                     &exact_deletions,
                     &exact_additions,
                     &mut exact_word_docids_writer,
-                );
-                let word = Some(w.to_string());
+                )?;
+                word = Some(w.to_string());
                 // clear buffers
                 deletions.clear();
                 additions.clear();
@@ -138,7 +138,7 @@ pub fn extract_word_docids<R: io::Read + io::Seek>(
                 exact_additions.clear();
             }
         } else {
-            let word = Some(w.to_string());
+            word = Some(w.to_string());
         }
 
         // merge all deletions
@@ -169,13 +169,13 @@ pub fn extract_word_docids<R: io::Read + io::Seek>(
     }
 
     if let Some(word) = word {
-        docids_into_writers(&word, &deletions, &additions, &mut word_docids_writer);
+        docids_into_writers(&word, &deletions, &additions, &mut word_docids_writer)?;
         docids_into_writers(
             &word,
             &exact_deletions,
             &exact_additions,
             &mut exact_word_docids_writer,
-        );
+        )?;
     }
 
     Ok((
@@ -253,7 +253,7 @@ where
             CboRoaringBitmapCodec::bytes_encode(deletions).map_err(|_| {
                 SerializationError::Encoding { db_name: Some(DOCID_WORD_POSITIONS) }
             })?,
-        );
+        )?;
     }
     // additions:
     if !additions.is_empty() {
@@ -262,7 +262,7 @@ where
             CboRoaringBitmapCodec::bytes_encode(additions).map_err(|_| {
                 SerializationError::Encoding { db_name: Some(DOCID_WORD_POSITIONS) }
             })?,
-        );
+        )?;
     }
 
     // insert everything in the same writer.
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 d86d09bc8..e185566ca 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
@@ -11,7 +11,7 @@ use super::helpers::{
 };
 use crate::error::SerializationError;
 use crate::index::db_name::DOCID_WORD_POSITIONS;
-use crate::proximity::{index_proximity, MAX_DISTANCE};
+use crate::proximity::{index_proximity, ProximityPrecision, MAX_DISTANCE};
 use crate::update::del_add::{DelAdd, KvReaderDelAdd, KvWriterDelAdd};
 use crate::update::settings::InnerIndexSettingsDiff;
 use crate::{DocumentId, Result};
@@ -24,9 +24,20 @@ use crate::{DocumentId, Result};
 pub fn extract_word_pair_proximity_docids<R: io::Read + io::Seek>(
     docid_word_positions: grenad::Reader<R>,
     indexer: GrenadParameters,
-    _settings_diff: &InnerIndexSettingsDiff,
+    settings_diff: &InnerIndexSettingsDiff,
 ) -> Result<grenad::Reader<BufReader<File>>> {
     puffin::profile_function!();
+    let any_deletion = settings_diff.old.proximity_precision == ProximityPrecision::ByWord;
+    let any_addition = settings_diff.new.proximity_precision == ProximityPrecision::ByWord;
+
+    // early return if the data shouldn't be deleted nor created.
+    if !any_deletion && !any_addition {
+        return tempfile::tempfile()
+            .map_err(Into::into)
+            .map(BufReader::new)
+            .and_then(grenad::Reader::new)
+            .map_err(Into::into);
+    }
 
     let max_memory = indexer.max_memory_by_thread();
 
@@ -79,6 +90,10 @@ pub fn extract_word_pair_proximity_docids<R: io::Read + io::Seek>(
 
         let (del, add): (Result<_>, Result<_>) = rayon::join(
             || {
+                if !any_deletion {
+                    return Ok(());
+                }
+
                 // deletions
                 if let Some(deletion) = KvReaderDelAdd::new(value).get(DelAdd::Deletion) {
                     for (position, word) in KvReaderU16::new(deletion).iter() {
@@ -108,6 +123,10 @@ pub fn extract_word_pair_proximity_docids<R: io::Read + io::Seek>(
                 Ok(())
             },
             || {
+                if !any_addition {
+                    return Ok(());
+                }
+
                 // additions
                 if let Some(addition) = KvReaderDelAdd::new(value).get(DelAdd::Addition) {
                     for (position, word) in KvReaderU16::new(addition).iter() {
diff --git a/milli/src/update/index_documents/extract/mod.rs b/milli/src/update/index_documents/extract/mod.rs
index a6b73efde..924561dea 100644
--- a/milli/src/update/index_documents/extract/mod.rs
+++ b/milli/src/update/index_documents/extract/mod.rs
@@ -9,7 +9,6 @@ mod extract_word_docids;
 mod extract_word_pair_proximity_docids;
 mod extract_word_position_docids;
 
-use std::collections::HashSet;
 use std::fs::File;
 use std::io::BufReader;
 
@@ -30,7 +29,6 @@ use self::extract_word_pair_proximity_docids::extract_word_pair_proximity_docids
 use self::extract_word_position_docids::extract_word_position_docids;
 use super::helpers::{as_cloneable_grenad, CursorClonableMmap, GrenadParameters};
 use super::{helpers, TypedChunk};
-use crate::proximity::ProximityPrecision;
 use crate::update::settings::InnerIndexSettingsDiff;
 use crate::{FieldId, Result};
 
@@ -200,12 +198,14 @@ fn run_extraction_task<FE, FS, M>(
     M: Send,
 {
     let current_span = tracing::Span::current();
+    /// TODO: remove clone
+    let settings_diff = settings_diff.clone();
 
     rayon::spawn(move || {
         let child_span = tracing::trace_span!(target: "indexing::extract::details", parent: &current_span, "extract_multiple_chunks");
         let _entered = child_span.enter();
         puffin::profile_scope!("extract_multiple_chunks", name);
-        match extract_fn(chunk, indexer, settings_diff) {
+        match extract_fn(chunk, indexer, &settings_diff) {
             Ok(chunk) => {
                 let _ = lmdb_writer_sx.send(Ok(serialize_fn(chunk)));
             }
@@ -235,50 +235,54 @@ fn send_original_documents_data(
         .thread_name(|index| format!("embedding-request-{index}"))
         .build()?;
 
-    rayon::spawn(move || {
-        for (name, (embedder, prompt)) in embedders {
-            let result = extract_vector_points(
-                documents_chunk_cloned.clone(),
-                indexer,
-                &field_id_map,
-                &prompt,
-                &name,
-            );
-            match result {
-                Ok(ExtractedVectorPoints { manual_vectors, remove_vectors, prompts }) => {
-                    let embeddings = match extract_embeddings(
+    if settings_diff.reindex_vectors() || !settings_diff.settings_update_only() {
+        /// TODO: remove clone
+        let settings_diff = settings_diff.clone();
+        rayon::spawn(move || {
+            for (name, (embedder, prompt)) in settings_diff.new.embedding_configs.clone() {
+                let result = extract_vector_points(
+                    documents_chunk_cloned.clone(),
+                    indexer,
+                    &settings_diff,
+                    &prompt,
+                    &name,
+                );
+                match result {
+                    Ok(ExtractedVectorPoints { manual_vectors, remove_vectors, prompts }) => {
+                        let embeddings = match extract_embeddings(
                         prompts,
                         indexer,
                         embedder.clone(),
                         &request_threads,
                     ) {
-                        Ok(results) => Some(results),
-                        Err(error) => {
-                            let _ = lmdb_writer_sx_cloned.send(Err(error));
-                            None
-                        }
-                    };
+                                Ok(results) => Some(results),
+                                Err(error) => {
+                                    let _ = lmdb_writer_sx_cloned.send(Err(error));
+                                    None
+                                }
+                            };
 
-                    if !(remove_vectors.is_empty()
-                        && manual_vectors.is_empty()
-                        && embeddings.as_ref().map_or(true, |e| e.is_empty()))
-                    {
-                        let _ = lmdb_writer_sx_cloned.send(Ok(TypedChunk::VectorPoints {
-                            remove_vectors,
-                            embeddings,
-                            expected_dimension: embedder.dimensions(),
-                            manual_vectors,
-                            embedder_name: name,
-                        }));
+                        if !(remove_vectors.is_empty()
+                            && manual_vectors.is_empty()
+                            && embeddings.as_ref().map_or(true, |e| e.is_empty()))
+                        {
+                            let _ = lmdb_writer_sx_cloned.send(Ok(TypedChunk::VectorPoints {
+                                remove_vectors,
+                                embeddings,
+                                expected_dimension: embedder.dimensions(),
+                                manual_vectors,
+                                embedder_name: name,
+                            }));
+                        }
+                    }
+
+                    Err(error) => {
+                        let _ = lmdb_writer_sx_cloned.send(Err(error));
                     }
                 }
-
-                Err(error) => {
-                    let _ = lmdb_writer_sx_cloned.send(Err(error));
-                }
             }
-        }
-    });
+        });
+    }
 
     // TODO: create a custom internal error
     let _ = lmdb_writer_sx.send(Ok(TypedChunk::Documents(original_documents_chunk)));
diff --git a/milli/src/update/index_documents/mod.rs b/milli/src/update/index_documents/mod.rs
index 6bc5b6ff9..c3b081c37 100644
--- a/milli/src/update/index_documents/mod.rs
+++ b/milli/src/update/index_documents/mod.rs
@@ -6,7 +6,6 @@ mod typed_chunk;
 
 use std::collections::{HashMap, HashSet};
 use std::io::{Read, Seek};
-use std::iter::FromIterator;
 use std::num::NonZeroU32;
 use std::result::Result as StdResult;
 
@@ -281,7 +280,7 @@ where
 
         let TransformOutput {
             primary_key,
-            settings_diff,
+            mut settings_diff,
             field_distribution,
             documents_count,
             original_documents,
@@ -319,13 +318,8 @@ where
         ) = crossbeam_channel::unbounded();
 
         // get the primary key field id
-        let primary_key_id = output.settings_diff.new.fields_ids_map.id(&primary_key).unwrap();
+        let primary_key_id = settings_diff.new.fields_ids_map.id(&primary_key).unwrap();
 
-        // get searchable fields for word databases
-        let searchable_fields =
-            self.index.searchable_fields_ids(self.wtxn)?.map(HashSet::from_iter);
-        // get filterable fields for facet databases
-        let faceted_fields = self.index.faceted_fields_ids(self.wtxn)?;
         // get the fid of the `_geo.lat` and `_geo.lng` fields.
         let mut field_id_map = self.index.fields_ids_map(self.wtxn)?;
 
@@ -348,12 +342,6 @@ where
             None => None,
         };
 
-        let stop_words = self.index.stop_words(self.wtxn)?;
-        let separators = self.index.allowed_separators(self.wtxn)?;
-        let dictionary = self.index.dictionary(self.wtxn)?;
-        let exact_attributes = self.index.exact_attributes_ids(self.wtxn)?;
-        let proximity_precision = self.index.proximity_precision(self.wtxn)?.unwrap_or_default();
-
         let pool_params = GrenadParameters {
             chunk_compression_type: self.indexer_config.chunk_compression_type,
             chunk_compression_level: self.indexer_config.chunk_compression_level,
diff --git a/milli/src/update/index_documents/transform.rs b/milli/src/update/index_documents/transform.rs
index 003353793..e82600683 100644
--- a/milli/src/update/index_documents/transform.rs
+++ b/milli/src/update/index_documents/transform.rs
@@ -1,12 +1,11 @@
 use std::borrow::Cow;
 use std::collections::btree_map::Entry as BEntry;
 use std::collections::hash_map::Entry as HEntry;
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 use std::fs::File;
 use std::io::{Read, Seek};
 
 use fxhash::FxHashMap;
-use heed::RoTxn;
 use itertools::Itertools;
 use obkv::{KvReader, KvReaderU16, KvWriter};
 use roaring::RoaringBitmap;
@@ -814,7 +813,8 @@ impl<'a, 'i> Transform<'a, 'i> {
         let settings_diff = InnerIndexSettingsDiff {
             old: old_inner_settings,
             new: new_inner_settings,
-            embedding_configs_updated: true,
+            embedding_configs_updated: false,
+            settings_update_only: false,
         };
 
         Ok(TransformOutput {
@@ -844,13 +844,16 @@ impl<'a, 'i> Transform<'a, 'i> {
                 obkv_writer.insert(id, val)?;
             }
         }
-        let new_obkv = KvReader::<FieldId>::new(&obkv_writer.into_inner()?);
+        let data = obkv_writer.into_inner()?;
+        let new_obkv = KvReader::<FieldId>::new(&data);
 
         // take the non-flattened version if flatten_from_fields_ids_map returns None.
-        let old_flattened = Self::flatten_from_fields_ids_map(&old_obkv, &mut old_fields_ids_map)?
-            .map_or_else(|| old_obkv, |bytes| KvReader::<FieldId>::new(&bytes));
-        let new_flattened = Self::flatten_from_fields_ids_map(&new_obkv, &mut new_fields_ids_map)?
-            .map_or_else(|| new_obkv, |bytes| KvReader::<FieldId>::new(&bytes));
+        let old_flattened = Self::flatten_from_fields_ids_map(&old_obkv, &mut old_fields_ids_map)?;
+        let old_flattened =
+            old_flattened.as_deref().map_or_else(|| old_obkv, KvReader::<FieldId>::new);
+        let new_flattened = Self::flatten_from_fields_ids_map(&new_obkv, &mut new_fields_ids_map)?;
+        let new_flattened =
+            new_flattened.as_deref().map_or_else(|| new_obkv, KvReader::<FieldId>::new);
 
         original_obkv_buffer.clear();
         flattened_obkv_buffer.clear();
diff --git a/milli/src/update/settings.rs b/milli/src/update/settings.rs
index ae4304fce..6c770c0a1 100644
--- a/milli/src/update/settings.rs
+++ b/milli/src/update/settings.rs
@@ -1010,6 +1010,13 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
             }
             Setting::NotSet => false,
         };
+
+        // if any changes force a reindexing
+        // clear the vector database.
+        if update {
+            self.index.vector_arroy.clear(self.wtxn)?;
+        }
+
         Ok(update)
     }
 
@@ -1077,6 +1084,7 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
             old: old_inner_settings,
             new: new_inner_settings,
             embedding_configs_updated,
+            settings_update_only: true,
         };
 
         if inner_settings_diff.any_reindexing_needed() {
@@ -1087,20 +1095,23 @@ impl<'a, 't, 'i> Settings<'a, 't, 'i> {
     }
 }
 
-pub(crate) struct InnerIndexSettingsDiff {
-    pub old: InnerIndexSettings,
-    pub new: InnerIndexSettings,
+#[derive(Clone)]
+pub struct InnerIndexSettingsDiff {
+    pub(crate) old: InnerIndexSettings,
+    pub(crate) new: InnerIndexSettings,
 
     // TODO: compare directly the embedders.
-    pub embedding_configs_updated: bool,
+    pub(crate) embedding_configs_updated: bool,
+
+    pub(crate) settings_update_only: bool,
 }
 
 impl InnerIndexSettingsDiff {
-    fn any_reindexing_needed(&self) -> bool {
+    pub fn any_reindexing_needed(&self) -> bool {
         self.reindex_searchable() || self.reindex_facets() || self.reindex_vectors()
     }
 
-    fn reindex_searchable(&self) -> bool {
+    pub fn reindex_searchable(&self) -> bool {
         self.old
             .fields_ids_map
             .iter()
@@ -1115,13 +1126,13 @@ impl InnerIndexSettingsDiff {
             || self.old.proximity_precision != self.new.proximity_precision
     }
 
-    fn reindex_facets(&self) -> bool {
-        let existing_fields = self.new.existing_fields;
+    pub fn reindex_facets(&self) -> bool {
+        let existing_fields = &self.new.existing_fields;
         if existing_fields.iter().any(|field| field.contains('.')) {
             return true;
         }
 
-        let old_faceted_fields = self.old.user_defined_faceted_fields;
+        let old_faceted_fields = &self.old.user_defined_faceted_fields;
         if old_faceted_fields.iter().any(|field| field.contains('.')) {
             return true;
         }
@@ -1129,13 +1140,13 @@ impl InnerIndexSettingsDiff {
         // If there is new faceted fields we indicate that we must reindex as we must
         // index new fields as facets. It means that the distinct attribute,
         // an Asc/Desc criterion or a filtered attribute as be added or removed.
-        let new_faceted_fields = self.new.user_defined_faceted_fields;
+        let new_faceted_fields = &self.new.user_defined_faceted_fields;
         if new_faceted_fields.iter().any(|field| field.contains('.')) {
             return true;
         }
 
         let faceted_updated =
-            (&existing_fields - &old_faceted_fields) != (&existing_fields - &new_faceted_fields);
+            (existing_fields - old_faceted_fields) != (existing_fields - new_faceted_fields);
 
         self.old
             .fields_ids_map
@@ -1145,9 +1156,13 @@ impl InnerIndexSettingsDiff {
             || faceted_updated
     }
 
-    fn reindex_vectors(&self) -> bool {
+    pub fn reindex_vectors(&self) -> bool {
         self.embedding_configs_updated
     }
+
+    pub fn settings_update_only(&self) -> bool {
+        self.settings_update_only
+    }
 }
 
 #[derive(Clone)]