diff --git a/api/core/rag/datasource/vdb/pgvector/pgvector.py b/api/core/rag/datasource/vdb/pgvector/pgvector.py
index d90707ebcd..25a10a1e48 100644
--- a/api/core/rag/datasource/vdb/pgvector/pgvector.py
+++ b/api/core/rag/datasource/vdb/pgvector/pgvector.py
@@ -166,7 +166,7 @@ class PGVector(BaseVector):
 
         with self._get_cursor() as cur:
             cur.execute(
-                f"""SELECT meta, text, ts_rank(to_tsvector(coalesce(text, '')), to_tsquery(%s)) AS score
+                f"""SELECT meta, text, ts_rank(to_tsvector(coalesce(text, '')), plainto_tsquery(%s)) AS score
                 FROM {self.table_name}
                 WHERE to_tsvector(text) @@ plainto_tsquery(%s)
                 ORDER BY score DESC