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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13109) Use scanner look ahead for timeranges as well
Date Thu, 26 Feb 2015 20:26:05 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13109?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14339093#comment-14339093
] 

Lars Hofhansl commented on HBASE-13109:
---------------------------------------

Doesn't quite work since we check the timeranges before the individual columns (and so the
column trackers have no way to manage their state - i.e. track when the current column is
done)

> Use scanner look ahead for timeranges as well
> ---------------------------------------------
>
>                 Key: HBASE-13109
>                 URL: https://issues.apache.org/jira/browse/HBASE-13109
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Lars Hofhansl
>            Priority: Minor
>         Attachments: 13109-0.98.txt
>
>
> This is a continuation of HBASE-9778.
> We've seen a scenario of a very slow scan over a region using a timerange that happens
to fall after the ts of any Cell in the region.
> Turns out we spend a lot of time seeking.
> Tested with a 5 column table, and the scan is 5x faster when the timerange falls before
all Cells' ts.
> We can use the lookahead hint introduced in HBASE-9778 to do opportunistic SKIPing before
we actually seek.



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