[SERVER-45211] Sharded cluster fails on mapReduce with output collection when namespace does not yet exist Created: 17/Dec/19 Updated: 27/Oct/23 Resolved: 18/Dec/19 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | MapReduce |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Improvement | Priority: | Major - P3 |
| Reporter: | Jeffrey Yemin | Assignee: | Backlog - Query Team (Inactive) |
| Resolution: | Works as Designed | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Assigned Teams: |
Query
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| Description |
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A Java driver test of mapReduce to a non-existent database exposes a difference in behavior between latest builds and the 4.2 release. We're seeing this error:
on latest sharded clusters. The test succeeds on all released versions of MongoDB. |
| Comments |
| Comment by James Wahlin [ 18/Dec/19 ] |
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This is expected behavior for the aggregation based mapReduce implementation and is inline with behavior for an aggregation pipeline with a $merge stage. There are a number of behaviors supported by the legacy mapReduce implementation that do not fit in with our current sharded architecture (another example being mapReduce sharding the output collection as part of cluster command invocation). While removal of these features will be backward breaking for some users, they will provide a more stable / correct implementation. |