[SERVER-30669] mapReduce on mongos should pass UUID for sharded output collection in MapReduceFinishCommand to shards Created: 15/Aug/17  Updated: 30/Oct/23  Resolved: 12/Sep/17

Status: Closed
Project: Core Server
Component/s: Sharding
Affects Version/s: 3.5.11
Fix Version/s: 3.6.0-rc0

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

Issue Links:
Depends
depends on SERVER-30703 make _configsvrShardCollection return... Closed
Gantt Dependency
has to be done before SERVER-30780 Map/reduce with sharded output tempor... Closed
has to be done after SERVER-31041 _configsvrShardCollection should retu... Closed
Related
is related to SERVER-30713 make mapReduce on mongos send UUID fo... Backlog
Backwards Compatibility: Fully Compatible
Sprint: Sharding 2017-08-21, Sharding 2017-09-11, Sharding 2017-10-02
Participants:

 Description   

If a sharded output collection specified in a mapReduce command on a cluster, currently the shards will generate their own UUIDs for the collection rather than using the UUID stored on the config server.

This is because each shard puts its results into a temporary collection (which is created with a self-generated UUID), then renames the temporary collection to the final sharded output collection.

Instead of letting the shard generate the UUID for the temporary collection itself, a 3.6 mongos should pass the UUID to use as part of the MapReduceFinishCommand. The shard should use this UUID when creating the temp collection.

A shard in fcv=3.6 should uassert if the UUID is not sent as part of the MapReduceFinishCommand.



 Comments   
Comment by Ramon Fernandez Marina [ 12/Sep/17 ]

Author:

{'username': u'EshaMaharishi', 'name': u'Esha Maharishi', 'email': u'esha.maharishi@mongodb.com'}

Message:SERVER-30669 mapReduce on mongos should pass UUID for sharded output collection in MapReduceFinishCommand to shards
Branch:master
https://github.com/mongodb/mongo/commit/978521eb3926867b30903781fd89d4acd931f0c4

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