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https://issues.apache.org/jira/browse/HBASE-9769?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13796408#comment-13796408
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Lars Hofhansl commented on HBASE-9769:
--------------------------------------
Interestingly it depends on which column(s) is (are) selected.
Some numbers: 4m rows, 5 cols each, 1 cf, 10 bytes values, VERSIONS=1.
Everything measured in seconds.
Without patch:
||Wildcard||Col 1||Col 2||Col 4||Col 5||Col 2+4||
|6.4|8.5|14.3|14.6|11.1|20.3|
With patch sample1:
||Wildcard||Col 1||Col 2||Col 4||Col 5||Col 2+4||
|6.4|8.4|8.9|9.9|6.4|10.0|
Variation here was +- 0.2s.
So with this patch scanning is 2x faster than without in some cases, and never
slower. No special hint needed, beyond declaring VERSIONS correctly.
> Improve performance of a Scanner with explicit column list when rows are
> small/medium size
> ------------------------------------------------------------------------------------------
>
> Key: HBASE-9769
> URL: https://issues.apache.org/jira/browse/HBASE-9769
> Project: HBase
> Issue Type: Improvement
> Components: Scanners
> Affects Versions: 0.98.0, 0.94.12, 0.96.0
> Reporter: Vladimir Rodionov
> Assignee: Vladimir Rodionov
> Attachments: 9769-0.94-sample1.txt, 9769-0.94-sample.txt
>
>
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