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https://issues.apache.org/jira/browse/CASSANDRA-9830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15197557#comment-15197557
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Marcus Eriksson commented on CASSANDRA-9830:
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Haven't read the patch, but after incremental repair sstables move from
unrepaired leveling to repaired leveling *if possible* - this means that a top
level sstable in the unrepaired leveling might get dropped to level 0 in the
repaired leveling without recompaction (we only mutate the repaired at field in
sstable metadata)
> Option to disable bloom filter in highest level of LCS sstables
> ---------------------------------------------------------------
>
> Key: CASSANDRA-9830
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9830
> Project: Cassandra
> Issue Type: New Feature
> Components: Compaction
> Reporter: Jonathan Ellis
> Assignee: Paulo Motta
> Priority: Minor
> Labels: performance
> Fix For: 3.x
>
>
> We expect about 90% of data to be in the highest level of LCS in a fully
> populated series. (See also CASSANDRA-9829.)
> Thus if the user is primarily asking for data (partitions) that has actually
> been inserted, the bloom filter on the highest level only helps reject
> sstables about 10% of the time.
> We should add an option that suppresses bloom filter creation on top-level
> sstables. This will dramatically reduce memory usage for LCS and may even
> improve performance as we no longer check a low-value filter.
> (This is also an idea from RocksDB.)
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