[SERVER-66283] Tailable cursors can miss writes on unreplicated capped collections Created: 06/May/22 Updated: 05/Feb/24 Resolved: 29/Dec/22 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | None |
| Affects Version/s: | None |
| Fix Version/s: | 6.3.0-rc0 |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Louis Williams | Assignee: | Louis Williams |
| Resolution: | Fixed | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Backwards Compatibility: | Fully Compatible | ||||||||||||||||
| Operating System: | ALL | ||||||||||||||||
| Sprint: | Execution Team 2022-07-11, Execution Team 2022-07-25, Execution Team 2022-08-08, Execution Team 2022-08-22, Execution Team 2022-09-05, Execution Team 2022-09-19, Execution Team 2022-10-03, Execution Team 2022-10-17, Execution Team 2022-10-31, Execution Team 2022-11-14, Execution Team 2022-12-12, Execution Team 2022-11-28, Execution Team 2022-12-26, Execution Team 2023-01-09 | ||||||||||||||||
| Participants: | |||||||||||||||||
| Description |
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Unreplicated capped collections do not serialize writes (see This problem has essentially existed since we implemented document-level locking in 3.0. Instead of also serializing writes to capped local collections, which would affect performance of inserts into the system.profile collection, I propose that we ban the usage of tailable cursors on unreplicated capped collections since they never worked correctly anyways. |
| Comments |
| Comment by Githook User [ 29/Dec/22 ] |
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Author: {'name': 'Louis Williams', 'email': 'louis.williams@mongodb.com', 'username': 'louiswilliams'}Message: This corrects previously incorrect behavior where tailable cursors on unreplicated capped This pushes non-oplog capped collection visibility logic outside of the storage engine layer |
| Comment by Gregory Noma [ 15/Dec/22 ] |
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louis.williams@mongodb.com I see this is in Blocked but it's not linked as dependent as on anything, is there a ticket this can be linked to? |
| Comment by Louis Williams [ 10/May/22 ] |
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More context: we unintentionally broke tailable cursors on the system.profile collection in We have three options:
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| Comment by Louis Williams [ 06/May/22 ] |
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This is essentially an alternative to SERVER-18934, which is a decent amount of work. |