[SERVER-79308] mongod and mongos change streams treat maxTimeMS differently Created: 25/Jul/23  Updated: 08/Aug/23  Resolved: 08/Aug/23

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

Type: Bug Priority: Major - P3
Reporter: Mickey Winters Assignee: Backlog - Query Execution
Resolution: Cannot Reproduce Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Query Execution
Participants:

 Description   

the behavior I seemed to observe is that mongod will ignore maxTimeMS. even if its lower than maxAwaitTimeMS it won't timeout the query. but on mongos it will hit a timeout if mongod doesn't respond before maxTimeMS. in the spirit of reducing behavior differences between replSets and sharded clusters we should fix this to have just one behavior. I tested this with 7.1 sharded/unsharded and 5.0 sharded/unsharded. and it seems 7.1 was the only one where it errored



 Comments   
Comment by Amr Elhelw [ 08/Aug/23 ]

Closing this issue since Bernard could not reproduce this.
mickey.winters@mongodb.com please re-open if you still think this is an issue.

Comment by Mickey Winters [ 26/Jul/23 ]

that makes sense. I guess my question now is more, do we want to change the behavior of mongod or mongos here to have less differences in behavior for invisible sharding, or are we just fine with leaving the difference. if a customer was specifying maxTimeMS and it was ignored and we secretly migrate them to a sharded cluster then suddenly their change stream would start erroring potentially

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