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Date: Wed, 26 Feb 2014 15:02:20 +0000 (UTC)
From: "Nicolas Liochon (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
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Subject: [jira] [Commented] (HBASE-10018) Change the location prefetch
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    [ https://issues.apache.org/jira/browse/HBASE-10018?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13912990#comment-13912990 ] 

Nicolas Liochon commented on HBASE-10018:
-----------------------------------------

v1:
 - remove the lock
 - does a small reversed scan instead of a getRowSomething and a scan
 - deprecates all the prefetch methods, keep the interfaces but the methods do nothing
 - when we were doing a locate *without* the cache, we were also removing the entry from the cache. We don't do that anymore.

> 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: 0.98.1, 0.99.0
>
>         Attachments: 10018.v1.patch
>
>
> 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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