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From "Saket Joshi" <>
Subject cassandra row cache
Date Thu, 13 Jan 2011 18:47:41 GMT

I am running a 15 node cluster ,version 0.6.8, Linux 64bit OS, using
mmap I/O, 6GB ram allocated. I have row cache enabled to 80000 keys
(mean row size is 2KB). I am observing a strange behaviour.. I query for
1.6 Million rows across the cluster and time taken is around 40 mins , I
query the same data again , the time now is 25 mins to fetch data (i am
expecting the cache to be warm now) , but i see row cache hit rate
around 30% . Now i request the same data 3rd time, time to fetch is
under 4 mins and cache hit ratios are 99% ... Does any one have an idea
why this may be happening ?





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