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https://issues.apache.org/jira/browse/CASSANDRA-9830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15089900#comment-15089900
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Carl Yeksigian commented on CASSANDRA-9830:
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Kicked off a new run without the flush step:
http://cstar.datastax.com/tests/id/8943a864-b647-11e5-b06f-0256e416528f
Yeah, it seems surprising we wouldn't be using significantly less memory for
the bloom filters, considering how many of the sstables are in the top level,
but it might be down to the compact step. We'll see what happens with this run.
> 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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