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https://issues.apache.org/jira/browse/CASSANDRA-8920?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wei Deng updated CASSANDRA-8920:
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Labels: compaction lcs performance (was: performance)
> Optimise sequential overlap visitation for checking tombstone retention in
> compaction
> -------------------------------------------------------------------------------------
>
> Key: CASSANDRA-8920
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8920
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Benedict
> Assignee: Benedict
> Priority: Minor
> Labels: compaction, lcs, performance
> Fix For: 2.2.0 beta 1
>
> Attachments: 8920.txt
>
>
> The IntervalTree only maps partition keys. Since a majority of users deploy a
> hashed partitioner the work is mostly wasted, since they will be evenly
> distributed across the full token range owned by the node - and in some cases
> it is a significant amount of work. We can perform a corroboration against
> the file bounds if we get a BF match as a sanity check if we like, but
> performing an IntervalTree search is significantly more expensive (esp. once
> murmur hash calculation memoization goes mainstream).
> In LCS, the keys are bounded, to it might appear that it would help, but in
> this scenario we only compact against like bounds, so again it is not helpful.
> With a ByteOrderedPartitioner it could potentially be of use, but this is
> sufficiently rare to not optimise for IMO.
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