Out of interest what does cfstats say about the bloom filter stats ? A high false positive could lead to a low key cache hit rate.
> Also, is there a way to warm start the key cache, meaning pre-load the amount > of keys I set as keys_cached? See key_cache_save_period when creating the CF. Cheers ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 15/02/2012, at 5:54 AM, Eran Chinthaka Withana wrote: > Hi, > > I'm using Cassandra 1.0.7 and I've set the keys_cached to about 80% (using > the numerical values). This is visible in cfstats too. But I'm getting less > than 20% (or sometimes even 0%) key cache hit rate. Well, the data access > pattern is not the issue here as I know they are retrieving the same row > multiple times. I'm using hector client with dynamic load balancing policy > with consistency ONE for both reads and writes. Any ideas on how to find the > issue and fix this? > > Here is what I see on cfstats. > > Key cache capacity: 16637958 > Key cache size: 16637958 > Key cache hit rate: 0.045454545454545456 > > Also, is there a way to warm start the key cache, meaning pre-load the amount > of keys I set as keys_cached? > > Thanks, > Eran
