[SERVER-16742] KEEP_MUTATIONS stage is not needed for storage engines supporting doc-level locking Created: 06/Jan/15  Updated: 15/Jan/15  Resolved: 08/Jan/15

Status: Closed
Project: Core Server
Component/s: Querying
Affects Version/s: None
Fix Version/s: 2.8.0-rc5

Type: Improvement Priority: Major - P3
Reporter: David Storch Assignee: David Storch
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Backwards Compatibility: Fully Compatible
Participants:

 Description   

When using the MMAP v1 storage engine, query stages in a saved state receive invalidation notifications when documents get updated or deleted. Some stages flag documents that are deleted. The set of flagged documents is then read by the KEEP_MUTATIONS stage, which re-checks these documents against the query and returns them if they still match.

The invalidation mechanism described above is used only for MMAP v1; query plans running against storage engines such as WiredTiger never receive invalidations and never flag mutated documents for review by the KEEP_MUTATIONS stage. The planner's analysis phase should only add KEEP_MUTATIONS if the storage engine is MMAP v1.



 Comments   
Comment by Githook User [ 08/Jan/15 ]

Author:

{u'username': u'dstorch', u'name': u'David Storch', u'email': u'david.storch@10gen.com'}

Message: SERVER-16742 doc-locking storage engines do not need the KEEP_MUTATIONS stage
Branch: master
https://github.com/mongodb/mongo/commit/0ab4bbc6ac0f299a7ebb5e0c156cdd127e52a349

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