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Date: Mon, 12 Dec 2011 21:35:31 +0000 (UTC)
From: "Mikhail Bautin (Commented) (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HBASE-4683) Always cache index blocks
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    [ https://issues.apache.org/jira/browse/HBASE-4683?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13167824#comment-13167824 ] 

Mikhail Bautin commented on HBASE-4683:
---------------------------------------

Actually shouldCacheDataOnRead is weird. It is true by default as long as block cache is enabled, unless it is explicitly disabled in cacheConf. So I don't really know if that particular line ever becomes a problem when block cache is enabled. 
                
> Always cache index blocks
> -------------------------
>
>                 Key: HBASE-4683
>                 URL: https://issues.apache.org/jira/browse/HBASE-4683
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Lars Hofhansl
>            Assignee: Mikhail Bautin
>            Priority: Minor
>             Fix For: 0.94.0
>
>         Attachments: 4683-v2.txt, 4683.txt
>
>
> This would add a new boolean config option: hfile.block.cache.datablocks
> Default would be true.
> Setting this to false allows HBase in a mode where only index blocks are cached, which is useful for analytical scenarios where a useful working set of the data cannot be expected to fit into the (aggregate) cache.
> This is the equivalent of setting cacheBlocks to false on all scans (including scans on behalf of gets).
> I would like to get a general feeling about what folks think about this.
> The change itself would be simple.
> Update (Mikhail): we probably don't need a new conf option. Instead, we will make index blocks cached by default.

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