Introduce a new facet_id_is_null_docids database in the index

milli/src/update/delete_documents.rs

@@ -245,6 +245,7 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
             field_id_docid_facet_strings: _,
             script_language_docids,
             facet_id_exists_docids,
+            facet_id_is_null_docids,
             documents,
         } = self.index;
 
@@ -523,6 +524,13 @@ impl<'t, 'u, 'i> DeleteDocuments<'t, 'u, 'i> {
             &self.to_delete_docids,
         )?;
 
+        // We delete the documents ids that are under the facet field id values.
+        remove_docids_from_facet_id_exists_docids(
+            self.wtxn,
+            facet_id_is_null_docids,
+            &self.to_delete_docids,
+        )?;
+
         self.index.put_soft_deleted_documents_ids(self.wtxn, &RoaringBitmap::new())?;
 
         Ok(DetailedDocumentDeletionResult {