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From Robert Coli <>
Subject Re: explanation of generated files and ops
Date Wed, 11 Aug 2010 04:41:09 GMT
On 8/9/10 9:00 PM, S Ahmed wrote:
> What exactly is stored in the "....-Filter.db" files?
Oh, didn't see this line.
Bloom filter (all keys in data file). A Bloom filter, is a 
space-efficient probabilistic data structure that is used to test 
whether an element is a member of a set. False positives are possible, 
but false negatives are not. Cassandra uses bloom filters to save IO 
when performing a key lookup: each SSTable has a bloom filter associated 
with it that Cassandra checks before doing any disk seeks, making 
queries for keys that don't exist almost free.


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