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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-10018) Change the location prefetch
Date Fri, 22 Nov 2013 18:28:35 GMT

    [ https://issues.apache.org/jira/browse/HBASE-10018?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13830199#comment-13830199
] 

Andrew Purtell commented on HBASE-10018:
----------------------------------------

IIRC, a colleague at Trend Micro contributed this code to speed up HBase MR job initialization.
There have been many changes to the client since, makes sense to redo this for current conditions.


> Change the location prefetch
> ----------------------------
>
>                 Key: HBASE-10018
>                 URL: https://issues.apache.org/jira/browse/HBASE-10018
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.98.0, 0.96.0
>            Reporter: Nicolas Liochon
>            Assignee: Nicolas Liochon
>            Priority: Minor
>             Fix For: 0.98.0, 0.96.1
>
>
> Issues with prefetching are:
> - we do two calls to meta: one for the exact row, one for the prefetch 
> - it's done in a lock
> - we take the next 10 regions. Why 10, why the 10 next?
> - is it useful if the table has 100K regions?
> Options are:
> - just remove it
> - replace it with a reverse scan: this would save a call
>  



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