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From Brandon Williams <>
Subject Re: configurable bloom filters (like hbase)
Date Wed, 14 Dec 2011 16:31:04 GMT

On Wed, Dec 14, 2011 at 4:52 AM, Radim Kolar <> wrote:
> Dne 11.11.2011 7:55, Radim Kolar napsal(a):
>> i have problem with large CF (about 200 billions entries per node). While
>> i can configure index_interval to lower memory requirements, i still have to
>> stick with huge bloom filters.
>> Ideal would be to have bloom filters configurable like in hbase. Cassandra
>> standard is about 1.05% false possitive but in my case i would be fine even
>> with 20% false positive rate. Data are not often read back. Most of them
>> will be never read before they expire via TTL.
> anybody other has problem that bloom filters are using too much memory in
> applications which do not needs to read written data often?
> I am looking at bloom filters memory used and it would be ideal to have in
> cassandra-1.1 ability to shrink bloom filters to about 1/10 of their size.
> Is possible to code something like this: save bloom filters to disk as usual
> but during load, transform them into something smaller at cost increasing FP
> rate?

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