diff --git a/lightrag/kg/postgres_impl.py b/lightrag/kg/postgres_impl.py
index a946cf0d..f0523b45 100644
--- a/lightrag/kg/postgres_impl.py
+++ b/lightrag/kg/postgres_impl.py
@@ -2375,7 +2375,7 @@ class PGVectorStorage(BaseVectorStorage):
                     insert_query = f"""
                         INSERT INTO {table_name} ({columns_str})
                         VALUES ({placeholders})
-                        ON CONFLICT DO NOTHING
+                        ON CONFLICT (workspace, id) DO NOTHING
                     """
 
                     # Construct dict for execute() method