[SERVER-15152] When evaluating plans, some index candidates cause complete index scan Created: 05/Sep/14 Updated: 28/Dec/17 Resolved: 18/Sep/14 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Querying |
| Affects Version/s: | 2.6.4 |
| Fix Version/s: | 2.6.5, 2.7.7 |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Asya Kamsky | Assignee: | David Storch |
| Resolution: | Done | Votes: | 2 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Operating System: | ALL | ||||||||||||||||||||||||
| Backport Completed: | |||||||||||||||||||||||||
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| Case: | (copied to CRM) | ||||||||||||||||||||||||
| Description |
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When running query during multiPlanRunner stage some combinations of values and data distribute can cause a fast query have a possible plan/index choice where full index scan (of a non-selective attribute) would be evaluated. Running explain(true) can show which index has unusually high nscanned. It seems during race-off the full scan is finished, causing some percentage of queries to be excessively slow. |
| Comments |
| Comment by Githook User [ 18/Sep/14 ] |
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Author: {u'username': u'dstorch', u'name': u'David Storch', u'email': u'david.storch@10gen.com'}Message: |
| Comment by David Storch [ 18/Sep/14 ] |
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Author: {u'username': u'dstorch', u'name': u'David Storch', u'email': u'david.storch@10gen.com'}Message: |