[SERVER-34460] Mongos will not pick up database versions for database entries it already has cached after setFCV 4.0 Created: 13/Apr/18 Updated: 13/Apr/18 Resolved: 13/Apr/18 |
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| Status: | Closed |
| Project: | Core Server |
| Component/s: | Sharding |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Major - P3 |
| Reporter: | Esha Maharishi (Inactive) | Assignee: | Esha Maharishi (Inactive) |
| Resolution: | Won't Fix | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Operating System: | ALL | ||||||||
| Sprint: | Sharding 2018-04-23 | ||||||||
| Participants: | |||||||||
| Description |
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This is because mongos will only refresh an entry it has already cached if it is told the entry is stale. However, it will only be told the entry is stale if it receives StaleDbVersion from some shard, which can only happen if it attaches a databaseVersion in the request to the shard (and of course, mongos won't attach a database version if its cache entry does not have a database version). |
| Comments |
| Comment by Esha Maharishi (Inactive) [ 13/Apr/18 ] |
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Closing as Won't Fix. We decided not to handle this in 4.0, since no new features in 4.0 depend on database versioning. Database versioning will start working correctly in 4.2, because to upgrade to 4.2, the mongoses must be restarted as v4.2, which clears all of their in-memory state (including the cache of database entries). (Note that 4.2 mongoses will always expect database entries to have database versions). |