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Posted to commits@cassandra.apache.org by "Benedict (JIRA)" <ji...@apache.org> on 2014/09/12 22:05:33 UTC

[jira] [Commented] (CASSANDRA-7915) Waiting for sync on the commit log could happen after writing to memtable

    [ https://issues.apache.org/jira/browse/CASSANDRA-7915?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14132022#comment-14132022 ] 

Benedict commented on CASSANDRA-7915:
-------------------------------------

I'm not totally convinced by this, although it's debatable. The issue, of course, is that the data becomes visible and can be read before it is considered 'durable' - meaning that you could lose the cluster, restore from CL, and find data is missing that was previously present. Users relying on batch CL probably would not like this scenario.

> Waiting for sync on the commit log could happen after writing to memtable
> -------------------------------------------------------------------------
>
>                 Key: CASSANDRA-7915
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7915
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Branimir Lambov
>            Priority: Minor
>
> Currently the sync wait is part of CommitLog.add, which is executed in whole before any memtable write. The time for executing the latter is thus added on top of the time for file sync, which seems unnecessary.
> Moving the wait to a call at the end of Keystore.apply should hide the memtable write time and may improve performance, especially for the batch sync strategy.



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