[SERVER-34482] system.indexes 3.4 to 3.6 upgrade semantics on wiredTiger may cause mongod 4.0 to fail to start up Created: 13/Apr/18 Updated: 29/Oct/23 Resolved: 30/Apr/18 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Upgrade/Downgrade |
| Affects Version/s: | None |
| Fix Version/s: | 4.0.0-rc0 |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Maria van Keulen | Assignee: | Maria van Keulen |
| 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: | Storage NYC 2018-05-07 | ||||
| Participants: | |||||
| Linked BF Score: | 0 | ||||
| Description |
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system.indexes does not receive a UUID upon setFCV from 3.4 to 3.6 regardless of storage engine. Mongod 4.0 only exempts system.indexes from the UUID startup check if the storage engine is MMAP. This means that if a user creates system.indexes on mongod 3.4 or earlier when using wiredTiger, upgrades to mongod 3.6, then upgrades to mongod 4.0, mongod 4.0 will fail to startup. One solution to avoid this issue is to drop system.indexes on startup if it fails the UUID check. |
| Comments |
| Comment by Githook User [ 01/May/18 ] |
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Author: {'email': 'maria@mongodb.com', 'name': 'Maria van Keulen', 'username': 'mvankeulen94'}Message: |
| Comment by Githook User [ 30/Apr/18 ] |
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Author: {'email': 'maria@mongodb.com', 'username': 'mvankeulen94', 'name': 'Maria van Keulen'}Message: It is possible for a user to explicitly create MMAP-specific system |
| Comment by Maria van Keulen [ 24/Apr/18 ] |
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In light of |
| Comment by Maria van Keulen [ 13/Apr/18 ] |
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I do not believe it is possible to create system.namespaces on (non-MMAP) mongod 3.4, but if it is possible for system.namespaces to exist on a non-MMAP mongod 3.4 node, system.namespaces will have this issue as well. |