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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-7868) HFile performance regression between 0.92 and 0.94
Date Mon, 18 Feb 2013 17:25:13 GMT

    [ https://issues.apache.org/jira/browse/HBASE-7868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13580721#comment-13580721
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Lars Hofhansl commented on HBASE-7868:
--------------------------------------

I think PE needs some TLC.

In it's current form it is not that useful (to say it bluntly), and it is 100% not obvious
how to use it (I had to look at the source code to figure out what the filterScan test is
supposed to do).

At the very least we should add to the help text that one should seed the table first with
a SequentialWriteTest picking the right of rows. The HBase wiki seems to imply that SequentialWriteTest
is automatically run unless we run it in M/R mode, but it looks like that is not true.

The help text does say to run FilterScanTest with --rows=20, not entirely sure why.

                
> HFile performance regression between 0.92 and 0.94
> --------------------------------------------------
>
>                 Key: HBASE-7868
>                 URL: https://issues.apache.org/jira/browse/HBASE-7868
>             Project: HBase
>          Issue Type: Bug
>          Components: io
>    Affects Versions: 0.94.5
>            Reporter: Matteo Bertozzi
>            Assignee: Matteo Bertozzi
>             Fix For: 0.94.6
>
>         Attachments: FilteredScan.png, hfileperf-graphs.png, performances.pdf, performances.pdf
>
>
> By HFilePerformanceEvaluation seems that 0.94 is slower then 0.92
> Looking at the profiler for the Scan path, seems that most of the time, compared to 92,
is spent in the metrics dictionary lookup. [~eclark] pointed out the new per family/block
metrics.
> By commenting the metrics call in HFileReaderV2, the performance seems to get better,
but maybe metrics is not the only problem.

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