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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:
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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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