我有一个集合，它将保存机器数据和移动数据，数据在channel上捕获并保持在单一级别，没有嵌入对象，结构如下{"Id":ObjectId("544e4b0ae4b039d388a2ae3a"),"DeviceTypeId":"DeviceType1","DeviceTypeParentId":"Parent1","DeviceId":"D1","ChannelName":"Login","Timestamp":ISODate("2013-07-23T19:44:09Z"),"Country":"India","Region":"Maharashtra","City":"Nasik","