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https://issues.apache.org/jira/browse/CASSANDRA-9829?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17715858#comment-17715858
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Jonathan Ellis commented on CASSANDRA-9829:
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Do we think UCS replaces substantially all LCS use cases, or just many of them?
> Dynamically adjust LCS level sizes
> ----------------------------------
>
> Key: CASSANDRA-9829
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9829
> Project: Cassandra
> Issue Type: New Feature
> Components: Local/Compaction
> Reporter: Jonathan Ellis
> Priority: Normal
> Labels: compaction, lcs, performance
> Fix For: 5.x
>
>
> LCS works best when the top level is full. Then 90% of reads can be served
> from a single sstable. By contrast if the top level is only 10% full then
> 90% of reads will be served from two. This results in worse performance as
> well as confused users.
> To address this, we can adjust the ideal top level size to how much data is
> actually in it (and set each corresponding lower level to 1/10 of the next
> one above).
> (This is an idea [from
> rocksdb|https://www.reddit.com/r/IAmA/comments/3de3cv/we_are_rocksdb_engineering_team_ask_us_anything/ct4asen].)
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