[SERVER-74568] SdamServerSelector sometimes doesn't fully respect client readPreference for config shard Created: 02/Mar/23  Updated: 29/Oct/23  Resolved: 10/Apr/23

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: 7.0.0-rc0

Type: Bug Priority: Major - P3
Reporter: Cheahuychou Mao Assignee: Wenqin Ye
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
related to SERVER-74281 Only attach minClusterTime read prefe... Closed
is related to SERVER-68440 In server selection, tags are deleted... Closed
is related to SERVER-74415 SdamServerSelector Does Not Respect R... Closed
Assigned Teams:
Sharding NYC
Backwards Compatibility: Fully Compatible
Operating System: ALL
Sprint: Sharding NYC 2023-04-17
Participants:
Linked BF Score: 154

 Description   

Currently, the SdamServerSelector has the logic to ignore the minClusterTime in the readPreference given to it if the timestamp is not satisfiable. When constructing the effective readPreference, it only gives 'pref' to the constructor. Consequently, the other configurations such as 'tags', 'maxStalenessSeconds', and 'hedgingMode' all get lost.  For shard remote targeting at least, minClusterTime is only specified when the shard is the config shard. Prior to PM-2290, there probably isn't a case where the config server is targeted with readPreference that contains tags and so on. That might be why this issue never surfaced. Starting from PM-2290, this is a bug that needs to be addressed since it can result in the external client readPreference not being fully respected (as shown in BF-27925), 



 Comments   
Comment by Githook User [ 10/Apr/23 ]

Author:

{'name': 'wenqinYe', 'email': 'wenqin908@gmail.com', 'username': 'wenqinYe'}

Message: SERVER-74568: SdamServerSelector sometimes doesn't fully respect client readPreference for config shard
Branch: master
https://github.com/mongodb/mongo/commit/358010c175ec0863cdfacb6ce172359d5972db87

Comment by Jack Mulrow [ 21/Mar/23 ]

Scheduling for the end of this project because it's possible either SERVER-74415 or SERVER-74281 resolve this or mitigate its impact in a catalog shard enabled cluster.

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