What are the stages in the .explain() output

Question

The docs give some examples of what can appear in the stage field, but I can't find a definitive list of what the valid values are in there and what they mean.

Stages are descriptive of the operation; e.g.

COLLSCAN for a collection scan

IXSCAN for scanning index keys

FETCH for retrieving documents

SHARD_MERGE for merging results from shards

Could anyone explain them to me, or point me at somewhere definitive?

Himanshu Bhandari · Answer 1 · 2016-04-09T11:05:31.283

-1

As I can see in the book "MongoDB Data Modeling", it is written that

There are four stages:

and than the name and description of each at page # 88, and as you wrote in the docs also only 4 are given so may be we can conclude that there are 4 only.

google books link

edited Apr 09 '16 at 11:05

answered Apr 09 '16 at 07:58

Himanshu Bhandari

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Thanks, I can't get to that book. There is definitely more than that four though. e.g. KEEP_MUTATIONS – BanksySan Apr 09 '16 at 09:21
Oh! Sorry, I wasn't aware of that. Should I remove my answer? – Himanshu Bhandari Apr 09 '16 at 10:05
No, maybe someone will come along and prove me wrong. – BanksySan Apr 09 '16 at 10:40
e.g. http://stackoverflow.com/questions/33011166/mongodb-keep-mutation-stage-explain – BanksySan Apr 09 '16 at 10:41

What are the stages in the .explain() output

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