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From "Brian Lindauer (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-2975) Upgrade MurmurHash to version 3
Date Sat, 30 Jul 2011 04:44:09 GMT
Upgrade MurmurHash to version 3
-------------------------------

                 Key: CASSANDRA-2975
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2975
             Project: Cassandra
          Issue Type: Improvement
          Components: Core
    Affects Versions: 0.8.3
            Reporter: Brian Lindauer
            Priority: Trivial


MurmurHash version 3 was finalized on June 3. It provides an enormous speedup and increased
robustness over version 2, which is implemented in Cassandra. Information here:

http://code.google.com/p/smhasher/

The reference implementation is here:
http://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp?spec=svn136&r=136

I have already done the work to port the (public domain) reference implementation to Java
in the MurmurHash class and updated the BloomFilter class to use the new implementation:

https://github.com/lindauer/cassandra/commit/cea6068a4a3e5d7d9509335394f9ef3350d37e93

Apart from the faster hash time, the new version only requires one call to hash() rather than
2, since it returns 128 bits of hash instead of 64.

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