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https://issues.apache.org/jira/browse/CASSANDRA-6109?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13784245#comment-13784245
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Jonathan Ellis commented on CASSANDRA-6109:
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I guess whether hotness or overlap is a more important criterion depends on
your goal:
# prioritizing by hotness helps speed reads up more, especially when you have a
lot of cold data sitting around
# prioritizing by overlap ratio reduces disk space and helps throw away
obsolete cells faster
I was hoping to tackle #1 here, but maybe that needs a separate strategy a la
CASSANDRA-5560.
For #2, CASSANDRA-5906 adds a HyperLogLog component that does a fantastic job
of letting us estimate overlap ratios.
> Consider coldness in STCS compaction
> ------------------------------------
>
> Key: CASSANDRA-6109
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6109
> Project: Cassandra
> Issue Type: New Feature
> Components: Core
> Reporter: Jonathan Ellis
> Assignee: Tyler Hobbs
> Fix For: 2.0.2
>
>
> I see two options:
> # Don't compact cold sstables at all
> # Compact cold sstables only if there is nothing more important to compact
> The latter is better if you have cold data that may become hot again... but
> it's confusing if you have a workload such that you can't keep up with *all*
> compaction, but you can keep up with hot sstable. (Compaction backlog stat
> becomes useless since we fall increasingly behind.)
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