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From "Daniel Doubleday (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-4303) Compressed bloomfilters
Date Fri, 01 Jun 2012 12:02:23 GMT


Daniel Doubleday commented on CASSANDRA-4303:

Out of curiosity because I already started experimenting in this direction:

Has anybody benchmarked the option to keep bloom filters on disk. I did some simple tests
and could read around 6M random ints / sec from a paged-in SegmentedFile. My line of thinking
was: why not letting the os decide where the memory should be allocated because its a tradeoff
sst vs other data kept in mem anyways.

I'm not close to a patch to do some real world testing so maybe you can save me from the effort
because someone else tried and learned that it does not make sense.
> Compressed bloomfilters
> -----------------------
>                 Key: CASSANDRA-4303
>                 URL:
>             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

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