[DOCS-2980] Comment on: "manual/core/aggregation-pipeline-optimization.txt" Created: 24/Mar/14 Updated: 25/Apr/14 Resolved: 25/Apr/14 |
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| 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 |
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| Days since reply: | 9 years, 42 weeks, 5 days ago | ||||||||
| Description |
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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 ] |
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Author: {u'username': u'kay-kim', u'name': u'kay', u'email': u'kay.kim@10gen.com'}Message: |
| Comment by Githook User [ 04/Apr/14 ] |
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Author: {u'username': u'tychoish', u'name': u'Sam Kleinman', u'email': u'samk@10gen.com'}Message: |