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Posted to commits@cassandra.apache.org by "Jonathan Ellis (JIRA)" <ji...@apache.org> on 2015/02/04 04:36:35 UTC
[jira] [Commented] (CASSANDRA-6633) Dynamic Resize of Bloom Filters
[ https://issues.apache.org/jira/browse/CASSANDRA-6633?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14304598#comment-14304598 ]
Jonathan Ellis commented on CASSANDRA-6633:
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bq. separate address spaces for each hash function
I'm not sure what you mean here. Bloom filters save space by combining hashes in a single bucket space, so I don't see how you can add separate spaces to that and still have a BF.
> Dynamic Resize of Bloom Filters
> -------------------------------
>
> Key: CASSANDRA-6633
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6633
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Benedict
> Priority: Minor
> Labels: performance
> Fix For: 3.0
>
>
> Dynamic resizing would be useful. The simplest way to achieve this is to have separate address spaces for each hash function, so that we may increase/decrease accuracy by simply loading/unloading another function (we could even do interesting stuff in future like alternating the functions we select if we find we're getting more false positives than should be expected);
> Faster loading/unloading would help this, and we could achieve this by mmapping the bloom filter representation on systems that we can mlock.
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