[SERVER-15273] Only allocate powerOfTwo sized records in regular collections Created: 16/Sep/14  Updated: 02/Aug/18  Resolved: 18/Oct/14

Status: Closed
Project: Core Server
Component/s: Storage
Affects Version/s: None
Fix Version/s: 2.7.8

Type: Task Priority: Major - P3
Reporter: Mathias Stearn Assignee: Mathias Stearn
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-15807 Validate Command no longer returns "p... Closed
is related to DOCS-4327 Change documentation to reflect chang... Closed
Tested
Backwards Compatibility: Minor Change
Participants:

 Description   

Going forward, MMAPv1 will only allocate powerOfTwo sized records, regardless of the flag. This is required to make the new freelist work correctly in O(1) time without any scanning.

This only applies to regular collections. In particular it will not apply to capped collections or indexes.



 Comments   
Comment by Mathias Stearn [ 18/Oct/14 ]

Users that were explicitly turning off powerOf2 will need to switch to the stronger noPadding mode from SERVER-15273. This should only be done on collections that never get deletes or growing updates.

Comment by Githook User [ 18/Oct/14 ]

Author:

{u'username': u'RedBeard0531', u'name': u'Mathias Stearn', u'email': u'mathias@10gen.com'}

Message: SERVER-15273 Only quantize to exact bucket sizes

Prep for new freelist implementation.
Branch: master
https://github.com/mongodb/mongo/commit/08319d688517af8ac88fe7054ea10f1f08c5bf2d

Comment by Mathias Stearn [ 17/Sep/14 ]

The usePowerOfTwo flags will be silently ignored, and we will just use powerOfTwo allocation in all cases.

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