0

I have a Collection exampled below. This data is pulled from an endpoint every twenty minutes on a cron job. 

{"id":AFFD6,"empty":8,"capacity":15,"ready":6,"t":1474370406,"_id":"kROabyTIQ5eNoIf1"}
    {"id":AFFD6,"empty":9,"capacity":15,"ready":5,"t":1474116005,"_id":"kX0DpoZ5fkMr2ezg"}
    {"id":AFFD6,"empty":9,"capacity":15,"ready":5,"t":1474684808,"_id":"ken1WRN47PTW159H"}
    {"id":AFFD6,"empty":9,"capacity":15,"ready":5,"t":1474117205,"_id":"kes1gDlG1sBjgV1R"}
    {"id":AFFD6,"empty":10,"capacity":15,"ready":4,"t":1474264806,"_id":"khILUjzGEPOn0c2P"}
    {"id":AFFD6,"empty":9,"capacity":15,"ready":5,"t":1474275606,"_id":"ko9r8u860es7E2hI"}
    {"id":AFFD6,"empty":9,"capacity":15,"ready":5,"t":1474591207,"_id":"kpLS6mCtkIiffTrN"}

I want to discard any document (row) that doesn't show a change in the empty (and consequently ready). My goal is to find the most recent time stamp where these values have changed with in this collection.

Better illustrated, I want to reduce it to where the values change as such:

{"id":AFFD6,"empty":8,"capacity":15,"ready":6,"t":1474370406,"_id":"kROabyTIQ5eNoIf1"}
{"id":AFFD6,"empty":9,"capacity":15,"ready":5,"t":1474117205,"_id":"kes1gDlG1sBjgV1R"}
{"id":AFFD6,"empty":10,"capacity":15,"ready":4,"t":1474264806,"_id":"khILUjzGEPOn0c2P"}
{"id":AFFD6,"empty":9,"capacity":15,"ready":5,"t":1474591207,"_id":"kpLS6mCtkIiffTrN"}

Can I do this at the in a MongoDB query? Or am I better off with a JavaScript filter function?

4

1 に答える 1

1

MongoDB では、インデックスに一意の制約を指定できます。これらの制約により、アプリケーションは、挿入されたフィールドに重複する値を持つドキュメントを挿入できなくなります。

次のコードを使用して一意にします

db.collection.createIndex( { "id": 1 }, { unique: true } )

詳細については、 MongoDB のドキュメントも参照してください。

于 2016-09-24T15:58:48.017 に答える