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https://issues.apache.org/jira/browse/CASSANDRA-11550?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15434138#comment-15434138
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Dikang Gu commented on CASSANDRA-11550:
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[~krummas] I got some time to test it in one of our cluster, I think the result
looks promising, after I change the fanout size from 10 to 6, I see ~40% drop
of the original data size, and the disk io dropped as well.
Take one node for example, before the change, the levels look like this:
SSTables in each level: [0, 12/10, 112/100, 98, 0, 0, 0, 0, 0]
SSTables in each level: [1, 11/10, 114/100, 99, 0, 0, 0, 0, 0]
After I change the fanout size to 6, it becomes:
SSTables in each level: [0, 6, 41/36, 120, 0, 0, 0, 0, 0]
SSTables in each level: [0, 6, 39/36, 123, 0, 0, 0, 0, 0]
which is more efficient, in terms of space amplification and write
amplification.
[~krummas] what do you think? Thanks!
> 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:
> 0001-make-fanout-size-for-leveledcompactionstrategy-to-be.patch
>
>
> 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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