diff --git a/src/emqttd_pubsub.erl b/src/emqttd_pubsub.erl
index bb8032c79..308be6184 100644
--- a/src/emqttd_pubsub.erl
+++ b/src/emqttd_pubsub.erl
@@ -39,11 +39,13 @@
 -boot_mnesia({mnesia, [boot]}).
 -copy_mnesia({mnesia, [copy]}).
 
-%% API Exports 
+%% API Exports
 -export([start_link/4]).
 
--export([create/2, subscribe/1, subscribe/2,
-         unsubscribe/1, unsubscribe/2, publish/1]).
+-export([create/2, lookup/2, subscribe/1, subscribe/2,
+         unsubscribe/1, unsubscribe/2, publish/1, delete/2]).
+
+%% Subscriptions API
 
 %% Local node
 -export([match/1]).
@@ -154,6 +156,30 @@ create(subscription, {SubId, Topic, Qos}) ->
         {aborted, Error} -> {error, Error}
     end.
 
+%%------------------------------------------------------------------------------
+%% @doc Lookup Topic or Subscription.
+%% @end
+%%------------------------------------------------------------------------------
+-spec lookup(topic | subscription, binary()) -> list().
+lookup(topic, Topic) ->
+    mnesia:dirty_read(topic, Topic);
+
+lookup(subscription, ClientId) ->
+    mnesia:dirty_read(subscription, ClientId).
+
+%%------------------------------------------------------------------------------
+%% @doc Delete Topic or Subscription.
+%% @end
+%%------------------------------------------------------------------------------
+delete(topic, _Topic) ->
+    {error, unsupported};
+
+delete(subscription, ClientId) when is_binary(ClientId) ->
+    mnesia:dirty_deleate({subscription, ClientId});
+
+delete(subscription, {ClientId, Topic}) when is_binary(ClientId) ->
+    mnesia:async_dirty(fun remove_subscriptions/2, [ClientId, [Topic]]).
+
 %%------------------------------------------------------------------------------
 %% @doc Subscribe Topics
 %% @end
@@ -363,7 +389,7 @@ remove_subscriptions(SubId, Topics) ->
     lists:foreach(fun(Topic) ->
          Pattern = #mqtt_subscription{subid = SubId, topic = Topic, qos = '_'},
          Records = mnesia:match_object(subscription, Pattern, write),
-         [delete_subscription(Record) || Record <- Records]
+         lists:foreach(fun delete_subscription/1, Records)
      end, Topics).
 
 delete_subscription(Record) ->
diff --git a/src/emqttd_session.erl b/src/emqttd_session.erl
index e2606ae5d..dde925ab0 100644
--- a/src/emqttd_session.erl
+++ b/src/emqttd_session.erl
@@ -483,7 +483,7 @@ handle_cast(Msg, State) ->
 %% Dispatch Message
 handle_info({dispatch, Topic, Msg}, Session = #session{subscriptions = Subscriptions})
     when is_record(Msg, mqtt_message) ->
-    dispatch(fixqos(Topic, Msg, Subscriptions), Session);
+    dispatch(tune_qos(Topic, Msg, Subscriptions), Session);
 
 handle_info({timeout, awaiting_ack, PktId}, Session = #session{client_pid = undefined,
                                                                awaiting_ack = AwaitingAck}) ->
@@ -603,7 +603,7 @@ dispatch(Msg = #mqtt_message{qos = QoS}, Session = #session{message_queue = MsgQ
             hibernate(Session#session{message_queue = emqttd_mqueue:in(Msg, MsgQ)})
     end.
 
-fixqos(Topic, Msg = #mqtt_message{qos = PubQos}, Subscriptions) ->
+tune_qos(Topic, Msg = #mqtt_message{qos = PubQos}, Subscriptions) ->
     case dict:find(Topic, Subscriptions) of
         {ok, SubQos} when PubQos > SubQos ->
             Msg#mqtt_message{qos = SubQos};