[SERVER-12949] MapReduce not doing incremental reduces when needed Created: 27/Feb/14 Updated: 11/Jul/16 Resolved: 17/Mar/14 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | MapReduce |
| Affects Version/s: | 2.6.0-rc0 |
| Fix Version/s: | 2.6.0-rc2 |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Kaloian Manassiev | Assignee: | Kaloian Manassiev |
| Resolution: | Done | Votes: | 0 |
| Labels: | 26qa | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Attachments: |
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| Operating System: | ALL | |||||||||||||||||
| Steps To Reproduce: | Original Title: mapreduce stats have changed between 2.4 and 2.6 Start mongo.exe and execute the following script (succeeds against 2.4 server and fails against 2.6 server):
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| Description |
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The mapreduce reduce count statistic has changed between 2.4 and 2.6. It is possible that it was incorrect before and has been fixed in 2.6, but this has to be verified. To reproduce, see the script in the repro steps section. In 2.4, the reduce count is 30 and in 2.6 it is 10. The value in 2.6 seems more reasonable, given that the number of distinct ids emitted is 10, but this has to be confirmed. |
| Comments |
| Comment by Githook User [ 17/Mar/14 ] |
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Author: {u'username': u'kaloianm', u'name': u'Kaloian Manassiev', u'email': u'kaloian.manassiev@mongodb.com'}Message: Also adds a JS unit test to ensure this behaviour doesn't change (cherry picked from commit acc47ab1b993d1abc295974200ffc57d98f4b80e) |
| Comment by Githook User [ 17/Mar/14 ] |
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Author: {u'username': u'kaloianm', u'name': u'Kaloian Manassiev', u'email': u'kaloian.manassiev@mongodb.com'}Message: Also adds a JS unit test to ensure this behaviour doesn't change |
| Comment by Daniel Pasette (Inactive) [ 03/Mar/14 ] |
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repro'd on 2.4 (after removing the mergeChunk cmd). I don't know what work has happened that would cause this change though so definitely want to explain it. |