我有一个mongo集合。我的收藏可以这样认为:{"kwId":"123445","p1":"15""p2":"25","date":"2017-01-28"}{"kwId":"123446","p1":"25""p2":"30","date":"2017-01-28"}{"kwId":"123445","p1":"35""p2":"40","date":"2017-01-27"}{"kwId":"123446","p1":"30""p2":"50","date":"2017-01-27"}对于每个日期，我有大约44k份文件。比方说，我想找出具有相同kwId但不同日期(例如2017-01