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From "Andrew Purtell (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-4487) The increment operation can release the rowlock before sync-ing the Hlog
Date Fri, 30 Sep 2011 17:03:45 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4487?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13118193#comment-13118193
] 

Andrew Purtell commented on HBASE-4487:
---------------------------------------

My comment lines up with Stack's on the code review, basically: This is a new code path for
increments, and it means that one cannot guarantee that any individual increment has been
committed to the WAL. For the increment case this walks back some representations we make
about HBase for the sake of performance. I have mixed feelings about that. This should be
configurable. Happy to agree the default is "enabled".

I believe there is another JIRA somewhere about making different config examples for users
depending on their risk tolerance or interest in performance. Enabling this and deferred flushing
etc. makes sense in a "performance" profile; conversely turned off in a "strict" profile.
                
> The increment operation can release the rowlock before sync-ing the Hlog
> ------------------------------------------------------------------------
>
>                 Key: HBASE-4487
>                 URL: https://issues.apache.org/jira/browse/HBASE-4487
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>             Fix For: 0.94.0
>
>         Attachments: appendNoSync4.txt, appendNoSync5.txt, appendNoSync6.txt
>
>
> This allows for better throughput when there are hot rows.I have seen this change make
a single row update improve from 400 increments/sec/server to 4000 increments/sec/server.

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