View the cache-hit ratio in Cassandra

As of version 1.2, the key cache and row cache are global to make better use of the off-heap functionality. Unfortunately, this means those stats are no longer available on the column family level.

These stats are available from the command line via nodetool info (last 2 lines of output).

e.g:

 [ec2-user@ip-172-31-45-42 ~]$ ./apache-cassandra-2.0.4/bin/nodetool info  
 Token      : (invoke with -T/--tokens to see all 256 tokens)  
 ID        : 0f694f54-4ec8-4730-a6d9-02c34bb1b847  
 Gossip active  : true  
 Thrift active  : true  
 Native Transport active: true  
 Load       : 3.48 MB  
 Generation No  : 1407836588  
 Uptime (seconds) : 2094  
 Heap Memory (MB) : 542.97 / 1014.00  
 Data Center   : datacenter1  
 Rack       : rack1  
 Exceptions    : 0  
 Key Cache    : size 1608 (bytes), capacity 52428800 (bytes), 83 hits, 101 requests, 0.822 recent hit rate, 14400 save period in seconds  
 Row Cache    : size 0 (bytes), capacity 0 (bytes), 0 hits, 0 requests, NaN recent hit rate, 0 save period in seconds