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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Index interval tuning
Date Wed, 11 May 2011 15:44:50 GMT
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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