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https://issues.apache.org/jira/browse/HBASE-11331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14030948#comment-14030948
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Vladimir Rodionov commented on HBASE-11331:
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These two statements contradict each other:
{quote}
Maintaining data in its compressed form in the block cache will greatly
increase our effective blockcache size and should show a meaning improvement in
cache hit rates in well designed applications.
{quote}
{quote}
The idea here is to lazily decompress/decrypt blocks when they're consumed,
rather than as soon as they're pulled off of disk.
{quote}
You either keep blocks compressed in a cache and decompress them on demand (1)
or you decompress them lazily and keep them decompressed after that (2). What
does "lazy decompression" means in this case? If you cache blocks on reads only
(most of the time and default behavior) - there is no much sense in a lazy
decompression, because your block will be accessed immediately after it got
into the cache. Lazy decompression makes sense only if you cache blocks on
writes, but in this case (2) contradicts (1) as I mentioned already.
> [blockcache] lazy block decompression
> -------------------------------------
>
> Key: HBASE-11331
> URL: https://issues.apache.org/jira/browse/HBASE-11331
> Project: HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: Nick Dimiduk
> Assignee: Nick Dimiduk
> Attachments: HBASE-11331.00.patch
>
>
> Maintaining data in its compressed form in the block cache will greatly
> increase our effective blockcache size and should show a meaning improvement
> in cache hit rates in well designed applications. The idea here is to lazily
> decompress/decrypt blocks when they're consumed, rather than as soon as
> they're pulled off of disk.
> This is related to but less invasive than HBASE-8894.
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