What are the values for RecentBloomFilterFalsePositives and BloomFilterFalsePositives the non ratio ones ? ----------------- Aaron Morton Freelance Cassandra Developer @aaronmorton http://www.thelastpickle.com
On 11 May 2011, at 19:53, Héctor Izquierdo Seliva wrote: > El mié, 11-05-2011 a las 14:24 +1200, aaron morton escribió: >> 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. >> >> Cheers > > 0.7.5, and I am no longer using key cache. I get the bloom filter stats > via jmx. BloomFilterFalsePositiveRatio is always stuck at 1.0. > RecentBloomFilterFalsePositiveRation fluctuates from 0 to 1.0 with no > intermediate values. > > As for the index interval settings, I changed it from 128 to 256 and > memory consumption was just a tad lower but read performance was worse > by a few ms, so not much to gain there. > >> ----------------- >> Aaron Morton >> Freelance Cassandra Developer >> @aaronmorton >> http://www.thelastpickle.com >> >> On 11 May 2011, at 10:38, Chris Burroughs wrote: >> >>> On 05/10/2011 02:12 PM, Peter Schuller wrote: >>>>> That reminds me, my false positive ration is stuck at 1.0, so I guess >>>>> bloom filters aren't doing a lot for me. >>>> >>>> That sounds unlikely unless you're hitting some edge case like reading >>>> a particular row that happened to be a collision, and only that row. >>>> This is from JMX stats on the column family store? >>>> >>> >>> (From jmx) I also see BloomFilterFalseRatio stuck at 1.0 on my >>> production nodes. The only values that RecentBloomFilterFalseRatio had >>> over the past several minutes were 0.0 and 1.0. While I can't prove >>> that isn't accurate, it is very suspicions. >>> >>> The code looked reasonable until I got to SSTableReader, which was too >>> complicated to just glance through. >> > >
