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https://issues.apache.org/jira/browse/HBASE-20045?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16372406#comment-16372406
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stack commented on HBASE-20045:
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What you thinking [~jmspaggi] ? We'd have to cache the block from the compacted
file. We'd map the evicted block locations to new blocks in the compacted file
and then preemptively cache these? They'd be coming in on first hit anyways but
you'd like to save on that bit of latency reading in the block from HDFS?
> When running compaction, cache recent blocks.
> ---------------------------------------------
>
> Key: HBASE-20045
> URL: https://issues.apache.org/jira/browse/HBASE-20045
> Project: HBase
> Issue Type: New Feature
> Components: BlockCache, Compaction
> Affects Versions: 2.0.0-beta-1
> Reporter: Jean-Marc Spaggiari
> Priority: Major
>
> HBase already allows to cache blocks on flush. This is very useful for
> usecases where most queries are against recent data. However, as soon as
> their is a compaction, those blocks are evicted. It will be interesting to
> have a table level parameter to say "When compacting, cache blocks less than
> 24 hours old". That way, when running compaction, all blocks where some data
> are less than 24h hold, will be automatically cached.
>
> Very useful for table design where there is TS in the key but a long history
> (Like a year of sensor data).
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