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From "Raymond Liu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-7952) Remove update() and Improve ExplicitColumnTracker performance.
Date Thu, 28 Feb 2013 04:09:22 GMT

    [ https://issues.apache.org/jira/browse/HBASE-7952?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13589170#comment-13589170
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Raymond Liu commented on HBASE-7952:
------------------------------------

And no matter how the original useage is. I think the current implementation also can not
ensure that things work out correctly, if columns are feed to the column not in order. as
long as the last target column is reached, the columntracker will return next row without
waiting for next out of order column to come. And if the same column with different ts is
feed to tracker in different order from different HFile, say c1(t1) , c2, c1(t2), the c1(t2)
will still be ignored in the array list solution. So the current solution also not really
help with the case that column not feed to tracker in order (if this case really need in some
usage) 
                
> 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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