[SERVER-46432] Enable mapReduce out to collection to run on secondaries Created: 26/Feb/20  Updated: 06/Dec/22

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

Type: Task Priority: Major - P3
Reporter: Mihai Andrei Assignee: Backlog - Query Execution
Resolution: Unresolved Votes: 0
Labels: qexec-team
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Backports
Assigned Teams:
Query Execution
Backport Requested:
v4.4
Sprint: Query 2020-04-06, Query 2020-04-20
Participants:

 Description   

Note that mapReduce will not work as written with secondary read preference on a replica set because all mapReduce commands will be unconditionally sent to the primary. Besides test coverage, this ticket will remove this check and also update the following test as well.



 Comments   
Comment by David Storch [ 09/Apr/20 ]

I'm removing this ticket from the "$out/$merge on secondaries" epic, since mapReduce improvements were not initially in scope. We should still consider backporting this to 4.4 once it lands, though.

Comment by David Storch [ 19/Mar/20 ]

arun.banala, as we discussed over our call today, we would like to achieve this test coverage by ensuring that in our various secondary reads passthroughs for jscore, the shell targets all mapReduce commands to the secondaries. We suspect that there is currently an issue around causal consistency working with secondary reads for mapReduce, so you may be blocked until mihai.andrei merges his fix for this.

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