[SERVER-1278] do cursors work properly in all cases with sharding? Created: 22/Jun/10  Updated: 12/Jul/16  Resolved: 22/Jul/10

Status: Closed
Project: Core Server
Component/s: Sharding
Affects Version/s: None
Fix Version/s: 1.5.6

Type: Bug Priority: Major - P3
Reporter: Dwight Merriman Assignee: Eliot Horowitz (Inactive)
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
is related to SERVER-937 check config change mid-cursor iterat... Closed
Operating System: ALL
Participants:

 Description   

I am guessing there are problems when migrates happen.

a couple different cases to consider.

we should have some tests too before closing the ticket : have a cursor, force a migrate, do getmore...



 Comments   
Comment by Eliot Horowitz (Inactive) [ 08/Mar/11 ]

Yes, this is really fixed.

Comment by Andrew Armstrong [ 08/Mar/11 ]

Hmm is this really fixed?

Dwight's latest comment makes me nervous that its possible a query can miss data if its mid migration - for both serial and parallel queries.

Comment by Dwight Merriman [ 29/Jul/10 ]

what about scatter/gather scenarios? positive no dups etc. then?

Comment by Alberto Lerner [ 22/Jul/10 ]

Fixed by SERVER-937
http://github.com/mongodb/mongo/commit/4308df6f3b8a4e0fa962fa01c3bf73ca9ceca527

Comment by auto [ 22/Jul/10 ]

Author:

{'login': 'alerner', 'name': 'Alberto Lerner', 'email': 'alerner@10gen.com'}

Message: SERVER-1278 sharding/cursor1.js shouldn't really work, fix upcoming
http://github.com/mongodb/mongo/commit/aeb3276abc6ce210a57caf1a2deacc13c9a735dc

Comment by auto [ 22/Jul/10 ]

Author:

{'login': 'alerner', 'name': 'Alberto Lerner', 'email': 'alerner@10gen.com'}

Message: SERVER-1278 Test that cursor survives split/move of chunks
http://github.com/mongodb/mongo/commit/36f2ba408298f3ea9e637502970d605daf7eb172

Comment by auto [ 22/Jul/10 ]

Author:

{'login': 'alerner', 'name': 'Alberto Lerner', 'email': 'alerner@10gen.com'}

Message: SERVER-1278 Hook objsLeftInBatch to js code
http://github.com/mongodb/mongo/commit/419ba813d304ecf312df9f6988748b6408713526

Comment by auto [ 22/Jul/10 ]

Author:

{'login': 'alerner', 'name': 'Alberto Lerner', 'email': 'alerner@10gen.com'}

Message: SERVER-1278 Expose cursor buffer remains to js testing
http://github.com/mongodb/mongo/commit/f9c5b67d117ce2d3383f678d9c1d406e6ae0046f

Comment by Dwight Merriman [ 22/Jun/10 ]

great - well we need test cases anyway.

if there is an update, i guess the versions on the two shards will vary, but i think that is ok as we do not do promise snapshotting.

Comment by Eliot Horowitz (Inactive) [ 22/Jun/10 ]

I think it actually is handled correctly.
we don't delete the data on the FROM server until the client is done or times out

Comment by Dwight Merriman [ 22/Jun/10 ]

above is talking about user / client cursors (with cursorids)

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