[
https://issues.apache.org/jira/browse/CASSANDRA-9830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15218622#comment-15218622
]
Marcus Eriksson commented on CASSANDRA-9830:
--------------------------------------------
bq. The basic idea is to regenerate BF if dropping to level 0 during
anti-compaction
Problem is that if the repaired sstable fits within the repaired range we don't
anticompact, we just mutate the repairedAt value for the sstable
[here|https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/db/compaction/CompactionManager.java#L610-L621]
> 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.)
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
