diff --git a/gnes/indexer/chunk/numpy.py b/gnes/indexer/chunk/numpy.py
index e700e72b..7b6254ba 100644
--- a/gnes/indexer/chunk/numpy.py
+++ b/gnes/indexer/chunk/numpy.py
@@ -23,11 +23,15 @@
 
 
 class NumpyIndexer(BaseChunkIndexer):
+    """An exhaustive search indexer using numpy
+    The distance is computed as L1 distance normalized by the number of dimension
+    """
 
-    def __init__(self, num_bytes: int = None, *args, **kwargs):
+    def __init__(self, is_binary: bool = False, *args, **kwargs):
         super().__init__()
-        self.num_bytes = num_bytes
+        self._num_dim = None
         self._vectors = None  # type: np.ndarray
+        self._is_binary = is_binary
         self._key_info_indexer = ListKeyIndexer()
 
     def add(self, keys: List[Tuple[int, Any]], vectors: np.ndarray, weights: List[float], *args,
@@ -35,12 +39,12 @@ def add(self, keys: List[Tuple[int, Any]], vectors: np.ndarray, weights: List[fl
         if len(vectors) % len(keys) != 0:
             raise ValueError('vectors bytes should be divided by doc_ids')
 
-        if not self.num_bytes:
-            self.num_bytes = vectors.shape[1]
-        elif self.num_bytes != vectors.shape[1]:
+        if not self._num_dim:
+            self._num_dim = vectors.shape[1]
+        elif self._num_dim != vectors.shape[1]:
             raise ValueError(
                 "vectors' shape [%d, %d] does not match with indexer's dim: %d" %
-                (vectors.shape[0], vectors.shape[1], self.num_bytes))
+                (vectors.shape[0], vectors.shape[1], self._num_dim))
 
         if self._vectors is not None:
             self._vectors = np.concatenate([self._vectors, vectors], axis=0)
@@ -48,16 +52,17 @@ def add(self, keys: List[Tuple[int, Any]], vectors: np.ndarray, weights: List[fl
             self._vectors = vectors
         self._key_info_indexer.add(keys, weights)
 
-    def query(self, keys: np.ndarray, top_k: int, *args, **kwargs
-              ) -> List[List[Tuple]]:
-        keys = np.expand_dims(keys, axis=1)
-        dist = keys - np.expand_dims(self._vectors, axis=0)
-        score = np.sum(np.minimum(np.abs(dist), 1), -1) / self.num_bytes
+    def query(self, keys: np.ndarray, top_k: int, *args, **kwargs) -> List[List[Tuple]]:
+        dist = np.abs(np.expand_dims(keys, axis=1) - np.expand_dims(self._vectors, axis=0))
+
+        if self._is_binary:
+            dist = np.minimum(dist, 1)
+
+        score = np.sum(dist, -1) / self._num_dim
 
         ret = []
         for ids in score:
-            rk = sorted(enumerate(ids), key=lambda x: -x[1])
+            rk = sorted(enumerate(ids), key=lambda x: x[1])[:top_k]
             chunk_info = self._key_info_indexer.query([j[0] for j in rk])
-
             ret.append([(*r, s) for r, s in zip(chunk_info, [j[1] for j in rk])])
         return ret
diff --git a/gnes/service/base.py b/gnes/service/base.py
index 10dcf1a8..34d696ea 100644
--- a/gnes/service/base.py
+++ b/gnes/service/base.py
@@ -267,7 +267,7 @@ def post_handler(self, msg: 'gnes_pb2.Message', *args, **kwargs):
     def _hook_warn_body_type_change(self, msg: 'gnes_pb2.Message', old_body_type: str, *args, **kwargs):
         new_type = msg.WhichOneof('body')
         if new_type != old_body_type:
-            self.logger.warning('message body is changed from %s to %s' % (new_type, old_body_type))
+            self.logger.warning('message body is changed from %s to %s' % (old_body_type, new_type))
 
     def _hook_sort_response(self, msg: 'gnes_pb2.Message', *args, **kwargs):
         if 'sorted_response' in self.args and self.args.sorted_response and msg.response.search.topk_results: