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From "T Jake Luciani (JIRA)" <>
Subject [jira] Updated: (CASSANDRA-1555) Considerations for larger bloom filters
Date Tue, 07 Dec 2010 12:46:12 GMT


T Jake Luciani updated CASSANDRA-1555:

    Attachment: 1555_v5.txt

Fixed the murur hash problem (the issue was with use of bytebuffers)
Re-factored the code a bit. Put hash32 and hash64 into MurmurHash class.

Overall I'm happy with this implementation, especially the sstable descriptor approach.


Stu, I wasn't able to apply your latest patch for tests could you rebase against v5?

> Considerations for larger bloom filters
> ---------------------------------------
>                 Key: CASSANDRA-1555
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Stu Hood
>            Assignee: Ryan King
>             Fix For: 0.8
>         Attachments: 1555_v5.txt, addendum-to-1555.txt, cassandra-1555.tgz, CASSANDRA-1555v2.patch,
CASSANDRA-1555v3.patch.gz, CASSANDRA-1555v4.patch.gz
> To (optimally) support SSTables larger than 143 million keys, we need to support bloom
filters larger than 2^31 bits, which java.util.BitSet can't handle directly.
> A few options:
> * Switch to a BitSet class which supports 2^31 * 64 bits (Lucene's OpenBitSet)
> * Partition the java.util.BitSet behind our current BloomFilter
> ** Straightforward bit partitioning: bit N is in bitset N // 2^31
> ** Separate equally sized complete bloom filters for member ranges, which can be used
independently or OR'd together under memory pressure.
> All of these options require new approaches to serialization.

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