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From "Lars George (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13721) Improve shell scan performances when using LIMIT
Date Wed, 27 May 2015 19:09:21 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13721?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14561524#comment-14561524
] 

Lars George commented on HBASE-13721:
-------------------------------------

Sorry RAM, for some reason I was sure it only showed two. I seem mistaken, please disregard.

> Improve shell scan performances when using LIMIT
> ------------------------------------------------
>
>                 Key: HBASE-13721
>                 URL: https://issues.apache.org/jira/browse/HBASE-13721
>             Project: HBase
>          Issue Type: Bug
>          Components: shell
>    Affects Versions: 1.1.0
>            Reporter: Jean-Marc Spaggiari
>            Assignee: Jean-Marc Spaggiari
>             Fix For: 2.0.0, 0.98.13, 1.0.2, 1.2.0, 1.1.1
>
>         Attachments: HBASE-13721-v0-trunk.txt
>
>
> When doing a scan which is expected to return the exact same number of rows as the LIMIT
we give, we still scan the entire table until we return the row(s) and then test the numbers
of rows we have. This can take a lot of time.
> Example:
> scan 'sensors', { COLUMNS => ['v:f92acb5b-079a-42bc-913a-657f270a3dc1'], STARTROW
=> '000a', LIMIT => 1 }
> This is because we will break on the limit condition AFTER we ask for the next row. If
there is none, we scan the entire table than exit.
> Goal of this patch is to handle this specific case without impacting the others.



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