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https://issues.apache.org/jira/browse/HBASE-6371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13478537#comment-13478537
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Lars Hofhansl commented on HBASE-6371:
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Is this in the 0.89 branch, and is it finished?
Does this only change the compaction selection?
A feature I'd be interested in is separating old and new data, such it would
not typically be compacted into the same file(s) - even in a major compaction.
If there is hot new data and lot of older data that is only occasionally
queried, if old and new data ends up in the same set of files, scanning is
slow, because scanning the latest version only is hitting many more blocks then
necessary and old versions of KVs need to be skipped (and HFiles with only old
data could otherwise simply be ignored).
An approach LevelDB might be interesting. Here's a description:
http://code.google.com/p/leveldb/source/browse/doc/impl.html
Is that what we are trying to do with this?
> [89-fb] Tier based compaction
> -----------------------------
>
> Key: HBASE-6371
> URL: https://issues.apache.org/jira/browse/HBASE-6371
> Project: HBase
> Issue Type: Improvement
> Reporter: Akashnil
> Assignee: Liyin Tang
> Labels: noob
>
> 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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