Mongodb, find all latest mapping records only

Question

I have a mongodb collections with around 2000 millions data represents mobile devices. I will generate a device id when it rigister to my server, for some reasons, it may register multiple times, some there may be more than one deviceId for one device(imei)

The generate id is the collection id so it is unique. the collection is like

id  | imei  | createTime

Now I need to query all device mappings from this collection, but for the same imei, I need the latest device id.

In SQL I may write

select id, imei from table join ( select max(createTime), imei from table group by imei) as t2 on(imei, createTime). 

Is there a faster way in mongodb query?

Answer 1

要在mongo中完成分组，您可以使用较旧的分组依据或聚合框架