diff --git a/gnes/cli/parser.py b/gnes/cli/parser.py
index 342206ed..14bb238f 100644
--- a/gnes/cli/parser.py
+++ b/gnes/cli/parser.py
@@ -288,6 +288,9 @@ def set_indexer_parser(parser=None):
     if not parser:
         parser = set_base_parser()
     _set_sortable_service_parser(parser)
+    parser.add_argument('--as_response', type=ActionNoYes, default=True,
+                        help='convert the message type from request to response after indexing. '
+                             'turn it off if you want to chain other services after this index service.')
 
     return parser
 
diff --git a/gnes/service/indexer.py b/gnes/service/indexer.py
index f20edfc1..e9e9f7e9 100644
--- a/gnes/service/indexer.py
+++ b/gnes/service/indexer.py
@@ -36,16 +36,20 @@ def _handler_index(self, msg: 'gnes_pb2.Message'):
         #     print('!!! tid: %s, tmp_a: %r %r' % (threading.get_ident(), self._tmp_a, self._handler_index))
         from ..indexer.base import BaseChunkIndexer, BaseDocIndexer
         if isinstance(self._model, BaseChunkIndexer):
-            self._handler_chunk_index(msg)
+            is_changed = self._handler_chunk_index(msg)
         elif isinstance(self._model, BaseDocIndexer):
-            self._handler_doc_index(msg)
+            is_changed = self._handler_doc_index(msg)
         else:
             raise ServiceError(
                 'unsupported indexer, dont know how to use %s to handle this message' % self._model.__bases__)
-        msg.response.index.status = gnes_pb2.Response.SUCCESS
-        self.is_model_changed.set()
 
-    def _handler_chunk_index(self, msg: 'gnes_pb2.Message'):
+        if self.args.as_response:
+            msg.response.index.status = gnes_pb2.Response.SUCCESS
+
+        if is_changed:
+            self.is_model_changed.set()
+
+    def _handler_chunk_index(self, msg: 'gnes_pb2.Message') -> bool:
         embed_info = []
 
         for d in msg.request.index.docs:
@@ -59,13 +63,19 @@ def _handler_chunk_index(self, msg: 'gnes_pb2.Message'):
         if embed_info:
             vecs, doc_ids, offsets, weights = zip(*embed_info)
             self._model.add(list(zip(doc_ids, offsets)), np.stack(vecs), weights)
+            return True
         else:
             self.logger.warning('chunks contain no embedded vectors, the indexer will do nothing')
-
-    def _handler_doc_index(self, msg: 'gnes_pb2.Message'):
-        self._model.add([d.doc_id for d in msg.request.index.docs],
-                        [d for d in msg.request.index.docs],
-                        [d.weight for d in msg.request.index.docs])
+            return False
+
+    def _handler_doc_index(self, msg: 'gnes_pb2.Message') -> bool:
+        if msg.request.index.docs:
+            self._model.add([d.doc_id for d in msg.request.index.docs],
+                            [d for d in msg.request.index.docs],
+                            [d.weight for d in msg.request.index.docs])
+            return True
+        else:
+            return False
 
     def _put_result_into_message(self, results, msg: 'gnes_pb2.Message'):
         msg.response.search.ClearField('topk_results')