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From "Phabricator (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-4683) Always cache index and bloom blocks
Date Wed, 14 Dec 2011 01:58:31 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4683?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13168984#comment-13168984
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Phabricator commented on HBASE-4683:
------------------------------------

mbautin has commented on the revision "[jira] [HBASE-4683] Always cache index and bloom blocks".

INLINE COMMENTS
  src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderV2.java:293 Compactions mostly
consist of continuous reads and should not do a lot of seeks. But yes, this will cache index/bloom
blocks even in case of compactions. I guess I could add a unit test to make sure we really
don't utilize the block index during compactions, and we can explicitly disable them here.
Or we could leave it as it is in case compactions do use the block index in a limited way
(need to find out if that is the case).
  @jdcryans: any thoughts/suggestions on this?

REVISION DETAIL
  https://reviews.facebook.net/D807

                
> Always cache index and bloom 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: 0.92.0, 0.94.0
>
>         Attachments: 4683-v2.txt, 4683.txt, D807.1.patch, D807.2.patch, HBASE-4683-0.92-v2.patch,
HBASE-4683-v3.patch
>
>
> 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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