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From Jonathan Ellis <>
Subject Re: [jira] Commented: (CASSANDRA-68) Bloom filters have much higher false-positive rate than expected
Date Sun, 12 Apr 2009 04:11:32 GMT
On Sat, Apr 11, 2009 at 9:53 PM, Prashant Malik <> wrote:
> The results are a bit counter intuitive here I would have expected it to be
> faster with the same FP rate but   I am not sure why it is slower if you are
> just using a couple of hash functions and using double hashing.

Murmur is a higher-quality hash and takes more operations to achieve
its better key distribution.  But since the new implementation always
uses two calls to Murmur no matter how many hashes are needed it is
virtually constant time.

> I am sorry I haven't looked at the test code but have you tried it with
> large strings as keys ? e.g 128 byte keys , also with Longs.

The random strings generated are 128 bytes.


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