[DOCS-2980] Comment on: "manual/core/aggregation-pipeline-optimization.txt" Created: 24/Mar/14  Updated: 25/Apr/14  Resolved: 25/Apr/14

Status: Closed
Project: Documentation
Component/s: manual
Affects Version/s: None
Fix Version/s: v1.3.4

Type: Improvement Priority: Minor - P4
Reporter: Mathias Stearn Assignee: Kay Kim (Inactive)
Resolution: Done Votes: 1
Labels: collector-298ba4e7
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

Location: http://docs.mongodb.org/master/core/aggregation-pipeline-optimization/#aggregation-pipeline-sequence-optimization
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:27.0) Gecko/20100101 Firefox/27.0
Referrer: http://docs.mongodb.org/master/core/aggregation-pipeline/
Screen Resolution: 2560 x 1440
repo: docs
source: core/aggregation-pipeline-optimization


Issue Links:
Related
is related to DOCS-2981 agg rewrite Closed
Participants:
Days since reply: 9 years, 42 weeks, 5 days ago

 Description   

None of these optimizations are real. These are all special cases of other optimizations.

The last one is odd since if there is a group, it is better not to add the project. The general rule is that if only a subset of fields are needed, agg will figure that out and only use those fields in a way that is more efficient than an explicit $project. You can see what fields it thinks are needed by running an explain. A $project should only be added if agg gets it wrong.



 Comments   
Comment by Githook User [ 25/Apr/14 ]

Author:

{u'username': u'kay-kim', u'name': u'kay', u'email': u'kay.kim@10gen.com'}

Message: DOCS-2980 agg optimization
Branch: master
https://github.com/mongodb/docs/commit/63a097aff8bc611abaf39cc1c83d4f09b8936c1e

Comment by Githook User [ 04/Apr/14 ]

Author:

{u'username': u'tychoish', u'name': u'Sam Kleinman', u'email': u'samk@10gen.com'}

Message: DOCS-2980: write concern read-reflections
Branch: master
https://github.com/mongodb/docs/commit/db0172f7786bca6eb33200dd66c0c2366209facf

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