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https://issues.apache.org/jira/browse/CASSANDRA-11550?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15579164#comment-15579164
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Dikang Gu commented on CASSANDRA-11550:
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I test this in one of our cluster, in default fanout_size=10 case, the sstables
look like this: [1, 11/10, 135/100, 98, 0, 0, 0, 0, 0], in fanout_size=6 case,
the sstables look like this: [1, 7/6, 38/36, 142, 0, 0, 0, 0, 0]. So in this
case, after the change, the highest level for sstables is still level 3, and we
can see improvements (reduce) in space usage, write amplification, and
compaction cpu usage. I can see ~20% improvements on those areas.
Some graphs are attached.
> Make the fanout size for LeveledCompactionStrategy to be configurable
> ---------------------------------------------------------------------
>
> Key: CASSANDRA-11550
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11550
> Project: Cassandra
> Issue Type: New Feature
> Components: Compaction
> Reporter: Dikang Gu
> Assignee: Dikang Gu
> Labels: lcs
> Fix For: 3.x
>
> Attachments: bytes_compacted.png, cpu_nice.png,
> write_amplification.png
>
>
> Currently, the fanout size for LeveledCompactionStrategy is hard coded in the
> system (10). It would be useful to make the fanout size to be tunable, so
> that we can change it according to different use cases.
> Further more, we can change the size dynamically.
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