You can try slightly lowering the bloom_filter_fp_chance on your table. Otherwise, it's possible that you're repeatedly querying one or two partitions that always trigger a bloom filter false positive. You could try manually tracing a few queries on this table (for non-existent partitions) to see if the bloom filter rejects them.
Depending on your Cassandra version, your false positive ratio could be inaccurate: https://issues.apache.org/jira/browse/CASSANDRA-8525 There are also a couple of recent improvements to bloom filters: * https://issues.apache.org/jira/browse/CASSANDRA-8413 * https://issues.apache.org/jira/browse/CASSANDRA-9167 On Thu, Feb 18, 2016 at 1:35 AM, Anishek Agarwal <anis...@gmail.com> wrote: > Hello, > > We have a table with composite partition key with humungous cardinality, > its a combination of (long,long). On the table we have > bloom_filter_fp_chance=0.010000. > > On doing "nodetool cfstats" on the 5 nodes we have in the cluster we are > seeing "Bloom filter false ratio:" in the range of 0.7 -0.9. > > I thought over time the bloom filter would adjust to the key space > cardinality, we have been running the cluster for a long time now but have > added significant traffic from Jan this year, which would not lead to > writes in the db but would lead to high reads to see if are any values. > > Are there any settings that can be changed to allow better ratio. > > Thanks > Anishek > -- Tyler Hobbs DataStax <http://datastax.com/>
