[SERVER-45282] Unify how mongos and mongod default RWC caches handle deleted defaults document Created: 20/Dec/19  Updated: 29/Oct/23  Resolved: 08/Jan/20

Status: Closed
Project: Core Server
Component/s: Sharding
Affects Version/s: None
Fix Version/s: 4.3.3

Type: Task Priority: Major - P3
Reporter: Jack Mulrow Assignee: Jack Mulrow
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
is related to SERVER-44890 MongoD RWCDefaults gets refreshed thr... Closed
Backwards Compatibility: Fully Compatible
Sprint: Sharding 2020-01-13
Participants:

 Description   

Mongos periodically refreshes its default read write concern cache and will only replace the current defaults in the cache if the found defaults have a greater epoch. If the defaults document is deleted (or the config.settings collection is dropped), the refresh will return a default constructed RWConcernDefault, which has no epoch, so the cache will not be updated.

In contrast, on mongod the defaults are currently updated through a WUOW onCommit handler, and the cached defaults will be set to whatever the new document is parsed as, which would be a default constructed RWConcernDefault for a delete.

These behaviors should be unified. Either mongod can ignore the deleted defaults like mongos, or mongos can be made to pick up the deleted defaults.



 Comments   
Comment by Githook User [ 08/Jan/20 ]

Author:

{'name': 'Jack Mulrow', 'email': 'jack.mulrow@mongodb.com', 'username': 'jsmulrow'}

Message: SERVER-45282 Unify how mongos and mongod default RWC caches handle deleted defaults document
Branch: master
https://github.com/mongodb/mongo/commit/e3dd9e80e38f3528bc50c3e1115c46a0687885fa

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