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 ----------------- 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.
