[SERVER-27580] MapReduce should use dropTarget argument to rename rather than doing the drop itself Created: 04/Jan/17  Updated: 27/Oct/23  Resolved: 18/Nov/20

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

Type: Improvement Priority: Major - P3
Reporter: Mathias Stearn Assignee: Backlog - Query Team (Inactive)
Resolution: Gone away Votes: 0
Labels: query-44-grooming
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Query
Participants:

 Description   

Having renameCollection do the dropping makes it more atomic by doing it in a single WriteUnitOfWork and generating a single oplog entry. Currently, it is possible for the drop to become durable or replicate without the rename. Also it is possible for a secondary reader to see the state between the drop and rename.

Agg $out already uses dropTarget rather than an explicit drop.



 Comments   
Comment by Charlie Swanson [ 18/Nov/20 ]

This is no longer applicable now that mapReduce is implemented in terms of $out. I believe $out uses this option, so this is resolved.

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