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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-7952) Remove update() and Improve ExplicitColumnTracker performance.
Date Thu, 28 Feb 2013 06:39:13 GMT

    [ https://issues.apache.org/jira/browse/HBASE-7952?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13589245#comment-13589245
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stack commented on HBASE-7952:
------------------------------

I think should be in this change since you are in the area already and you have an understanding
that few have.

Regards the check, we don't run with asserts enabled so in production a key could come in
that sorts above the current kv.  But adding the extra compare of every kv would be a big
cost to take on.

Could the merge be thrown out of whack when a new file is added in after a flush?
                
> Remove update() and Improve ExplicitColumnTracker performance.
> --------------------------------------------------------------
>
>                 Key: HBASE-7952
>                 URL: https://issues.apache.org/jira/browse/HBASE-7952
>             Project: HBase
>          Issue Type: Improvement
>          Components: regionserver
>    Affects Versions: 0.94.1, 0.94.5
>            Reporter: Raymond Liu
>            Assignee: Raymond Liu
>             Fix For: 0.96.0
>
>         Attachments: HBASE_7952.patch
>
>
> In ColumnTracker.java, the update() method is not used by anyone now. And no one will
call checkColumn for different HFiles with update() in between files to re-walk through the
target columns. All columns will be feed to checkColumn() in order.
> So, within ExplicitColumnTracker, the target columns can be optimized to not dynamic
maintain a changing list of columns yet to match. Instead, just move index through it is enough.
> with this optimization to save the time for avoid reconstruct a columns array upon each
row, the checkColumn method's performance could be improved by 10-20%.

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