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https://issues.apache.org/jira/browse/HBASE-6371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13444318#comment-13444318
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Nicolas Spiegelberg commented on HBASE-6371:
--------------------------------------------

@Ted: what's the reason for the 89-fb tag? This is currently developed for this 
branch, but probably should be ported to trunk as well.  This is an improvement 
on the default algorithm, not an app specialization.
                
> [89-fb] Level based compaction
> ------------------------------
>
>                 Key: HBASE-6371
>                 URL: https://issues.apache.org/jira/browse/HBASE-6371
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Akashnil
>            Assignee: Akashnil
>
> Currently, the compaction selection is not very flexible and is not sensitive 
> to the hotness of the data. Very old data is likely to be accessed less, and 
> very recent data is likely to be in the block cache. Both of these 
> considerations make it inefficient to compact these files as aggressively as 
> other files. In some use-cases, the access-pattern is particularly obvious 
> even though there is no way to control the compaction algorithm in those 
> cases.
> In the new compaction selection algorithm, we plan to divide the candidate 
> files into different levels according to oldness of the data that is present 
> in those files. For each level, parameters like compaction ratio, minimum 
> number of store-files in each compaction may be different. Number of levels, 
> time-ranges, and parameters for each level will be configurable online on a 
> per-column family basis.

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