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https://issues.apache.org/jira/browse/HBASE-11331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14030968#comment-14030968
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Nick Dimiduk commented on HBASE-11331:
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In this implementation, the decompressed block does not replace the compressed
block in the cache. Decompression cost is paid on block access, every time. I
need to profile the scanner path to ensure a single request is not
decompressing the same block multiple times. For hot blocks, I expect this to
result in increased CPU load vs decompressing it only once. For a more evenly
distributed access pattern, this should greatly reduce the amount of disk seeks
because more data is cached. I believe the latter use-case is more common.
> [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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