added some comments

lightrag/kg/tidb_impl.py

@@ -211,6 +211,7 @@ class TiDBKVStorage(BaseKVStorage):
         return left_data
 
     async def index_done_callback(self) -> None:
+        # Ti handles persistence automatically
         pass
 
     async def drop(self) -> None:
@@ -339,15 +340,14 @@ class TiDBVectorDBStorage(BaseVectorStorage):
         return await self.db.query(SQL, params, multirows=True)
 
     async def delete_entity(self, entity_name: str) -> None:
-        """Delete a single entity by its name"""
         raise NotImplementedError
 
     async def delete_entity_relation(self, entity_name: str) -> None:
-        """Delete relations for a given entity by scanning metadata"""
         raise NotImplementedError
 
     async def index_done_callback(self) -> None:
-        raise NotImplementedError
+        # Ti handles persistence automatically
+        pass
 
 
 @final
@@ -489,6 +489,7 @@ class TiDBGraphStorage(BaseGraphStorage):
             return []
 
     async def index_done_callback(self) -> None:
+        # Ti handles persistence automatically
         pass
 
     async def delete_node(self, node_id: str) -> None: