[SERVER-9287] Decision to split chunk should happen on shard mongod, not on mongos Created: 08/Apr/13 Updated: 29/Oct/19 Resolved: 07/Jun/19 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Sharding |
| Affects Version/s: | None |
| Fix Version/s: | 4.2.0 |
| Type: | Improvement | Priority: | Major - P3 |
| Reporter: | Spencer Brody (Inactive) | Assignee: | Alyson Cabral (Inactive) |
| Resolution: | Done | Votes: | 9 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Backwards Compatibility: | Fully Compatible | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Backport Requested: |
v4.2
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| Sprint: | Sharding 2018-08-13 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Case: | (copied to CRM) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Description |
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As it is, it's possible to get oversized chunks if data is being written to the same chunk from different mongoses, as each mongos would only see a small amount of data going to that chunk and thus won't trigger a chunk split. If the decision on when to split a chunk happened on the shard, then it could know exactly when 64Mb (or whatever the chunk size has been set to) has been written to a chunk, and thus can trigger a split at the right time and prevent chunks from ever going over the chunk size. |
| Comments |
| Comment by Alyson Cabral (Inactive) [ 07/Jun/19 ] |
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I'm happy to announce that starting in MongoDB 4.2, the decision to split a chunk has moved from the mongos to the mongod. Check out the release announcement for MongoDB 4.2 and get started with the release candidate through our downloads center. The release candidate will be available in Atlas shortly. Please see the attached server tickets for further technical details.
Congratulations to matthew.saltz for his work on this project. |