[SERVER-47425] When 4.2 discovers log version 4 records on startup, continue to write log version 4 records Created: 08/Apr/20 Updated: 29/Oct/23 Resolved: 17/Apr/20 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Storage |
| Affects Version/s: | 4.2.6, 4.4.0 |
| Fix Version/s: | 4.2.6, 4.4.0-rc2 |
| Type: | Improvement | Priority: | Major - P3 |
| Reporter: | Daniel Gottlieb (Inactive) | Assignee: | Daniel Gottlieb (Inactive) |
| 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 | ||||||||||||||||||||
| Sprint: | Execution Team 2020-04-20 | ||||||||||||||||||||
| Participants: | |||||||||||||||||||||
| Description |
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Downgrading from 4.4 -> 4.2.6 -> 4.2.x (x < 6) is not allowed. The current state of 4.2.6 will always write out log version 3 which earlier 4.2 versions understand. However, earlier 4.2 versions will fail to startup on the checkpointed data files in a messy way (likely a seg fault) Instead, 4.2.6 could discover if it's reading log version 4 records at startup (which is only possible via a 4.4 downgrade) and choose to write out log version 4 records. This would result in earlier versions failing with an "incompatible log version" error. |
| Comments |
| Comment by Githook User [ 17/Apr/20 ] |
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Author: {'name': 'Daniel Gottlieb', 'email': 'daniel.gottlieb@mongodb.com', 'username': 'dgottlieb'}Message: |
| Comment by Daniel Gottlieb (Inactive) [ 10/Apr/20 ] |
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Re-opening as there's still a 4.4 test to add which requires the updated 4.2 to test in evergreen. |
| Comment by Githook User [ 10/Apr/20 ] |
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Author: {'name': 'Daniel Gottlieb', 'email': 'daniel.gottlieb@mongodb.com', 'username': 'dgottlieb'}Message: In the upgrade/downgrade lifetime of a MongoDB dbpath, WT log version 4 is first In this patch, 4.2.6+ will discover whether it's starting up on log version 3 |