What happens if you disable row cache? On Tue, May 25, 2010 at 4:53 AM, Ran Tavory <ran...@gmail.com> wrote: > It seems there's an error reporting the Key cache hit rate. The value is > always 0.0 and I have a feeling it's incorrect. This is seen both by using > notetool cfstats as well as accessing JMX directly > (org.apache.cassandra.db:type=Caches,keyspace=outbrain_kvdb,cache=KvAdsKeyCache > RecentHitRate) > <ColumnFamily CompareWith="BytesType" Name="KvAds" > RowsCached="10000000" > KeysCached="10000000"/> > Column Family: KvAds > SSTable count: 7 > Space used (live): 1288942061 > Space used (total): 1559831566 > Memtable Columns Count: 73698 > Memtable Data Size: 17121092 > Memtable Switch Count: 33 > Read Count: 3614433 > Read Latency: 0.068 ms. > Write Count: 3503269 > Write Latency: 0.024 ms. > Pending Tasks: 0 > Key cache capacity: 10000000 > Key cache size: 619624 > Key cache hit rate: 0.0 > Row cache capacity: 10000000 > Row cache size: 447154 > Row cache hit rate: 0.8460295730014572 > Compacted row minimum size: 387 > Compacted row maximum size: 31430 > Compacted row mean size: 631 > The Row cache hit rate looks good, 0.8 but Key cache hit rate always seems > to be 0.0 while the number of unique keys stays about 619624 for quite a > while. > Is it a real caching problem or just a reporting glitch?
-- Jonathan Ellis Project Chair, Apache Cassandra co-founder of Riptano, the source for professional Cassandra support http://riptano.com
