[SERVER-10452] Unify mongos cursor cache, remove explicit distinction between unsharded and sharded cursors Created: 07/Aug/13  Updated: 06/Dec/22  Resolved: 24/Aug/18

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

Type: Improvement Priority: Major - P3
Reporter: Greg Studer Assignee: Backlog - Query Team (Inactive)
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Query
Participants:

 Description   

... since distinguishing between sharded and unsharded collections in mongos is nontrivial and not correct when the sharding status changes. This also interferes with aggregation, since cursor type does not necessarily correspond to input collection sharding state.



 Comments   
Comment by Ian Whalen (Inactive) [ 24/Aug/18 ]

Although it would be desirable to share code between mongod and mongos cursor managers, we're not going to pursue that right now. the part of this ticket about sharded/unsharded cursors no longer applies due to the rewrite in 3.2.

Comment by Kaloian Manassiev [ 23/Aug/18 ]

I know in 3.2 we did some work on the mongos query execution path, but not sure if that unified the cursor managers. Passing on to query.

Comment by auto [ 08/Aug/13 ]

Author:

{u'username': u'gregstuder', u'name': u'Greg Studer', u'email': u'greg@10gen.com'}

Message: SERVER-10452 mongos should select cursor based on cursorid, not sharding state
Branch: master
https://github.com/mongodb/mongo/commit/17b3f0fa4e42735c2d233984bf61fab87b49dde3

Fix here is not 100% solution to this, we want to unify the getMore codepaths further and make the ShardedCursorCache saner.

The patch above is the minimal fix needed for aggregated cursors to work.

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