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https://issues.apache.org/jira/browse/HBASE-5369?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mikhail Bautin updated HBASE-5369:
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    Description: 
HBase reserves a large set memory for the block cache and the cached blocks 
will be age out in a LRU fashion. Obviously, we don't want to age out the 
blocks which are still hot. However, when the compactions are starting, these 
hot blocks may naturally be invalid. Considering that the block cache has 
already known which HFiles these hot blocks come from, the compaction selection 
algorithm could just simply skip compact these HFiles until these block cache 
become cold.


  was:
HBase reserves a large set memory for the block cache and the cached blocks 
will be age out in a LRU fashion. Obviously, we don't want to age out the 
blocks which are still hot. However, when the compactions are starting, these 
hot blocks may naturally be invalid. Considering that the block cache has 
already known which HFiles these hot blocks come from, the compaction selection 
algorithm could just simply skip compact these HFiles until these block cache 
become cold.
Furthermore, the HBase could compact multiple HFiles into two HFiles. One of 
them only contains hot blocks which are supposed be cached directly.


    
> Compaction selection based on the hotness of the HFile's block in the block 
> cache
> ---------------------------------------------------------------------------------
>
>                 Key: HBASE-5369
>                 URL: https://issues.apache.org/jira/browse/HBASE-5369
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Liyin Tang
>            Assignee: Liyin Tang
>
> HBase reserves a large set memory for the block cache and the cached blocks 
> will be age out in a LRU fashion. Obviously, we don't want to age out the 
> blocks which are still hot. However, when the compactions are starting, these 
> hot blocks may naturally be invalid. Considering that the block cache has 
> already known which HFiles these hot blocks come from, the compaction 
> selection algorithm could just simply skip compact these HFiles until these 
> block cache become cold.

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