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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-10047) postScannerFilterRow consumes a lot of CPU in tall table scans
Date Wed, 27 Nov 2013 01:22:35 GMT

     [ https://issues.apache.org/jira/browse/HBASE-10047?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Lars Hofhansl updated HBASE-10047:
----------------------------------

    Attachment: postScannerFilterRow.png

Imagine of the profiling session.
postScannerFilterRow uses more CPU than the ScanQueryMatcher.

This is from a sampler, so I do not suspect any profiling anomalies.
Removing that part of the code as a test does indeed yield a 25% improvement in the scan time.

Now, this is an extreme case: Tall table, one small column, 1 version. So maybe it's not worth
spending a lot of time on this.

> postScannerFilterRow consumes a lot of CPU in tall table scans
> --------------------------------------------------------------
>
>                 Key: HBASE-10047
>                 URL: https://issues.apache.org/jira/browse/HBASE-10047
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Lars Hofhansl
>         Attachments: postScannerFilterRow.png
>
>
> Continuing my profiling quest, I find that in scanning tall table (and filtering everything
on the server) a quarter of the time is now spent in the postScannerFilterRow coprocessor
hook.



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