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From aaron morton <aa...@thelastpickle.com>
Subject Re: Index interval tuning
Date Wed, 11 May 2011 20:48:19 GMT
Thanks
A

-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com

On 12 May 2011, at 03:44, Jonathan Ellis wrote:

> Close: the problem is we don't count *any* true positives *unless*
> cache is enabled.
> 
> Fix attached to https://issues.apache.org/jira/browse/CASSANDRA-2637.
> 
> On Wed, May 11, 2011 at 7:04 AM, Chris Burroughs
> <chris.burroughs@gmail.com> wrote:
>> On 05/10/2011 10:24 PM, aaron morton wrote:
>>> What version and what were the values for RecentBloomFilterFalsePositives and
BloomFilterFalsePositives ?
>>> 
>>> The bloom filter metrics are updated in SSTableReader.getPosition() the only
slightly odd thing I can see is that we do not count a key cache hit a a true positive for
the bloom filter. If there were a lot of key cache hits and a few false positives the ratio
would be wrong. I'll ask around, does not seem to apply to Hectors case though.
>> 
>> 0.7.1  No key cache.
>> 
>> BloomFilterFalsePositives: 48130
>> Read Count: 153973494
>> RecentBloomFilterFalsePositives: 4, 1, 2, 0, 0, 1
>> 
> 
> 
> 
> -- 
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of DataStax, the source for professional Cassandra support
> http://www.datastax.com


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