1
我需要返回集合中每个用户的最小client_timestamp值,但是我没有能够以这种方式获得$ min操作符。有没有办法让查询返回集合中所有user_id的最小client_timestamp?返回一个集合中的ISODate值的最小值
query = ??? db.collection.find(查询).distinct( “client_timestamp”)
实例文档结构:
{
"device_type" : "Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz (8173 MB)",
"user_id" : "17204977745451858462",
"organization_id" : "1",
"client_timestamp" : "2014-09-10T04:46:39.201Z",
"client_session_id" : "PpfprJalFTNDZa2Ag1wUQ5D2Mfw",
"_id" : "0de1611e-d835-4557-9948-cbbf88afa098"
}
{
"device_type" : "Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz (8173 MB)",
"user_id" : "17204977745451858462",
"organization_id" : "1",
"client_timestamp" : "2014-09-10T04:46:39.368Z",
"client_session_id" : "PpfprJalFTNDZa2Ag1wUQ5D2Mfw",
"_id" : "21e71acf-43e4-4a2d-b946-074fe7983034"
}