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From Eran Chinthaka Withana <>
Subject Key cache hit rate issue
Date Tue, 14 Feb 2012 16:54:50 GMT

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?


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