MongoDB get executionStats for aggregate query

Question

I am looking for a way to retrieve the executionStats for aggregations.

When using find(), I can retrieve them easily by using explain. Example output:

  "executionStats": {
    "nReturned": 332505,
    "executionTimeMillis": 1349,
    "totalKeysExamined": 332505,
    "totalDocsExamined": 332505,
    ...

But when using aggregations with explain enabled it won't return the stats shown above.

This and this is related but there is no viable solution given. Because this might have changed in the meantime, I opened this question.

Is there any way this can be done without measuring the stats on the client side?

Answer 1

Currently(MongoDB 3.2) aggregation does not support executionStats, with explain option in aggreagation you get some data related to query but there is no executionStats in it. It is proposed and you can check its status here

https://jira.mongodb.org/browse/SERVER-19758

Please upvote the issue if you want to implement this soon.

Answer 2

I was able to do it in the following way:

db.myUserCollection.explain("executionStats").aggregate([{$match: {firstName: "John"} }]);

Reference: https://jira.mongodb.org/browse/SERVER-19758

Answer 3

For me it works like this, you have this fixed in from version 3.5.5

It shows the execution plan and other metrics.

db.videos.explain('executionStats').aggregate([])

Answer 4

executionStats was not supported for mongo aggregation queries till mongodb v3.4. The issue has been fixed in v3.6. i.e. db.videos.explain('executionStats').aggregate([])