主要字段:{_id:1,connect_time:1,sid:1,delay:1}
片键:{connect_time:1}
索引:{_id:1}
{connect_time:1}
{sid:1}
查询1:connect_time:NumberLong(1406803324000)
查询2:{sid:"
查询3:{connect_time:NumberLong(),sid:"
查询4:{sid:"
查询5:{connect_time:NumberLong(),delay:47}
查询6:{delay:47,connect_time:NumberLong()}
查询7:单机环境:{delay:47,connect_time:NumberLong()}
片键只作为寻找shard(chunk)使用,找到shard之后,查询索引与单机相同