[DOCS-11731] Docs for SERVER-33538: mapReduce "replace" on a sharded output collection can lead to UUIDCatalog inconsistencies Created: 24/May/18  Updated: 29/Oct/23  Resolved: 17/Jul/18

Status: Closed
Project: Documentation
Component/s: None
Affects Version/s: None
Fix Version/s: 4.0.0-rc1, 3.6.6, 4.1.1

Type: Task Priority: Major - P3
Reporter: Kay Kim (Inactive) Assignee: Susan Kerschbaumer (Inactive)
Resolution: Fixed Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Documented
documents SERVER-33538 mapReduce "replace" on a sharded outp... Closed
Participants:
Days since reply: 5 years, 30 weeks, 1 day ago
Epic Link: DOCS: 4.0 Server

 Description   

Description:

If the out field for mapReduce has 'sharded: true', the output collection cannot be an existing unsharded collection. We fail the mapReduce command in this case.

Scope of changes:

 

https://docs.mongodb.com/manual/reference/command/mapReduce/index.html – add a note to the section that describes the "sharded" parameter in the out stage/

https://docs.mongodb.com/manual/reference/method/db.collection.mapReduce/index.html – ditto

 

clarify: core/map-reduce-sharded-collections.html

 

Impact to other docs outside of this product:

MVP:

Resources:

Engineering Ticket Description:

mapReduce with a sharded output collection assigns the UUID obtained from the config server to the final output collection. mapReduce "replace" will drop the existing output collection, which has the same UUID as the new output collection. Two-phase-drop may cause the dropCollection to finish after the renameCollection finishes, erroneously removing the UUIDCatalog entry for the output collection.



 Comments   
Comment by Githook User [ 17/Jul/18 ]

Author:

{'username': 'skerschb', 'name': 'skerschb', 'email': 'sue.kerschbaumer@10gen.com'}

Message: DOCS-11731: backport for 3.6.6 (mapreduce and sharded output collection)
Branch: v3.6
https://github.com/mongodb/docs/commit/fafb9e531305f629ceae2a254500cd2c3b792d21

Comment by Githook User [ 25/Jun/18 ]

Author:

{'username': 'skerschb', 'name': 'skerschb', 'email': 'sue.kerschbaumer@10gen.com'}

Message: DOCS-11731
Branch: master
https://github.com/mongodb/docs/commit/16c2094674cc707533f926aa38142f57cca89700

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