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From "Lars Hofhansl (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-4683) Create config option to only cache index blocks
Date Thu, 17 Nov 2011 23:07:52 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4683?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13152432#comment-13152432
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Lars Hofhansl commented on HBASE-4683:
--------------------------------------

Looks like it in the code. blockCache is only null if hfile.block.cache.size is set to 0.
If it is not null, the cache setting is already overridden for index blocks in HFileBlockIndex.seekToDataBlock.

I'll verify then close this if confirmed.

                
> Create config option to only cache index blocks
> -----------------------------------------------
>
>                 Key: HBASE-4683
>                 URL: https://issues.apache.org/jira/browse/HBASE-4683
>             Project: HBase
>          Issue Type: New Feature
>            Reporter: Lars Hofhansl
>            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.

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