[SERVER-16850] Remove support for touch command for RocksDB Created: 14/Jan/15  Updated: 17/May/19  Resolved: 15/Jan/15

Status: Closed
Project: Core Server
Component/s: Storage
Affects Version/s: 2.8.0-rc4
Fix Version/s: 3.0.0-rc6

Type: Task Priority: Minor - P4
Reporter: Daniel Alabi Assignee: Daniel Alabi
Resolution: Done Votes: 0
Labels: 28qa
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Related
related to SERVER-16797 Remove support for touch command for ... Closed
related to SERVER-16604 Improve integration with rocks Closed
Backwards Compatibility: Minor Change
Participants:

 Description   

We have removed support for the touch command for wiredTiger because the result of the touch command (data:

{numRanges:.., millis:}

) is very mmapv1 specific. 'numRanges' corresponds to the number of extents touched into memory for a particular collection.

Since the concept of extents also doesn't exist in RocksDB, the result of the touch command doesn't really make sense. Furthermore, the current implementation of touch within RocksDB just forces all data to go through the block cache once by literally using a RocksDB iterator to read in all the data for a column family (the corresponding one for a collection). This is equivalent to doing a collection scan.

I've discussed this with Matt, Igor, and Siying.



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

Author:

{u'username': u'alabid', u'name': u'alabid', u'email': u'alabidan@gmail.com'}

Message: SERVER-16850 Remove support for touch command for RocksDB storage engine

Closes #908

Signed-off-by: Benety Goh <benety@mongodb.com>
Branch: master
https://github.com/mongodb/mongo/commit/48453bc2cb2f8f15cd69305d7526917ecf213211

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