diff --git a/src/db_store_mongo.erl b/src/db_store_mongo.erl
index 389d585..c1c50de 100644
--- a/src/db_store_mongo.erl
+++ b/src/db_store_mongo.erl
@@ -25,9 +25,14 @@
 init(Host, Port) ->
 	{ok, Conn} = mongo_connection:start_link({Host, Port}),
 	?I(?FMT("connect mongodb ~p:~p success", [Host, Port])),
+	init(Conn),
+	Conn.
+
+init(Conn) ->
 	enable_text_search(Conn),
 	ensure_search_index(Conn),
-	Conn.
+	% TODO: numid index ?	
+	ok.
 
 close(Conn) ->
 	mongo_connection:stop(Conn).
@@ -89,16 +94,15 @@ index(Conn, Hash) when is_list(Hash) ->
 	end.
 
 insert(Conn, Hash, Name, Length, Files) when is_list(Hash) ->
-	NewDoc = create_torrent_desc(Hash, Name, Length, 1, Files),
+	NewDoc = create_torrent_desc(Conn, Hash, Name, Length, 1, Files),
 	mongo_do(Conn, fun() ->
-		%mongo:insert(?COLLNAME, NewDoc)
-		% since the doc may already exist (inc_announce failed), i update the doc here
+		% the doc may already exist because the other process has inserted before
 		Sel = {'_id', list_to_binary(Hash)},
 		mongo:update(?COLLNAME, Sel, NewDoc, true)
 	end).
 
 unsafe_insert(Conn, Tors) when is_list(Tors) ->
-	Docs = [create_torrent_desc(Hash, Name, Length, 1, Files) || 
+	Docs = [create_torrent_desc(Conn, Hash, Name, Length, 1, Files) || 
 				{Hash, Name, Length, Files} <- Tors],
 	mongo:do(unsafe, master, Conn, ?DBNAME, fun() ->
 		mongo:insert(?COLLNAME, Docs)
@@ -135,7 +139,7 @@ enable_text_search(Conn) ->
 		mongo:command(Cmd)
 	end).
 
-create_torrent_desc(Hash, Name, Length, Announce, Files) ->
+create_torrent_desc(Conn, Hash, Name, Length, Announce, Files) ->
 	NameArray = case string_split:split(Name) of
 		{error, L, D} ->
 			?E(?FMT("string split failed(error): ~p ~p", [L, D])),
@@ -146,6 +150,8 @@ create_torrent_desc(Hash, Name, Length, Announce, Files) ->
 		{ok, R} -> R 
 	end,
 	{'_id', list_to_binary(Hash),
+      % steven told me it's necessary for sphinx, what if the doc already exists ?
+	  numid, db_system:get_torrent_id(Conn), 
 	  name, list_to_binary(Name),
 	  name_array, NameArray,
 	  length, Length,
diff --git a/src/db_system.erl b/src/db_system.erl
index c728258..56b1710 100644
--- a/src/db_system.erl
+++ b/src/db_system.erl
@@ -13,11 +13,30 @@
 		 stats_day_at/2,
 		 stats_day_at_slave/2,
 		 stats_get_peers/1]).
+-export([get_torrent_id/1]).
+-compile(export_all).
 -define(DBNAME, dht_system).
 -define(COLLNAME, system).
 -define(HASH_BATCH_KEY, <<"hashbatch">>).
 -define(STATS_COLLNAME, stats).
+-define(TORRENT_ID_KEY, <<"torrentid">>).
 
+% increase the seed and return the new id
+get_torrent_id(Conn) ->
+	Cmd = {findAndModify, ?COLLNAME, query, {'_id', ?TORRENT_ID_KEY},
+		update, {'$inc', {seed, 1}}, new, false, upsert, true},
+	Ret = mongo:do(safe, master, Conn, ?DBNAME, fun() ->
+		mongo:command(Cmd)
+	end),
+	case bson:lookup(value, Ret) of
+		{undefined} ->
+			0;
+		{} ->
+			0;
+		{Obj} ->
+			{Seed} = bson:lookup(seed, Obj),
+			Seed
+	end.
 
 %% batch index
 inc_batch_rindex(Conn) ->
@@ -104,4 +123,10 @@ stats_ensure_today(TodaySecs) ->
 			Doc	
 	end.
 
+%%
+test_torrent_id() ->
+	{ok, Conn} = mongo_connection:start_link({localhost, 27017}),
+	ID = get_torrent_id(Conn),
+	ID.
+
 
diff --git a/src/hash_reader/db_hash_reader_sup.erl b/src/hash_reader/db_hash_reader_sup.erl
index 0f59aa8..955bed0 100644
--- a/src/hash_reader/db_hash_reader_sup.erl
+++ b/src/hash_reader/db_hash_reader_sup.erl
@@ -45,6 +45,9 @@ start_link(IP, Port, Size) ->
 start_link(IP, Port, Size, OtherProcess) ->
 	PoolName = mongodb_conn_pool_name,
 	mongo_sup:start_pool(PoolName, 5, {IP, Port}),
+	% ensure index
+	Conn = mongo_pool:get(PoolName),
+	db_store_mongo:init(Conn),
 	supervisor:start_link({local, srv_name()}, ?MODULE, [PoolName, Size, OtherProcess]).
 
 srv_name() ->