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https://issues.apache.org/jira/browse/CASSANDRA-4303?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13287509#comment-13287509
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Pavel Yaskevich commented on CASSANDRA-4303:
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In addition for it to be slower it's also not a good idea to mmap BF because
you give all cards to the kernel to page out contents of the BF in any moment
necessary to handle other I/O traffic which would lead to page faults on the
critical BF operations in unpredictable manner since memory mappings operate on
the page cache basis.
> Compressed bloomfilters
> -----------------------
>
> Key: CASSANDRA-4303
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4303
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Brandon Williams
> Fix For: 1.2
>
>
> Very commonly, people encountering an OOM need to increase their bloom filter
> false positive ratio to reduce memory pressure, since BFs tend to be the
> largest shareholder. It would make sense if we could alleviate the memory
> pressure from BFs with compression while maintaining the FP ratio (at the
> cost of a bit of cpu) that some users have come to expect. One possible
> implementation is at http://code.google.com/p/javaewah/
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