Query to find out hit ratio of Oracle

To find out Library cache hit ratio

select sum(PINS-RELOADS)/sum(PINS)*100 "Library hit ratio"
from v$librarycache

Details Library Cache Hit Ratio
Query more details about the hit ratio from each library cache item.
SQL> SELECT namespace, gethitratio
FROM v$librarycache
WHERE gethitratio > 0


To find out Dictionary cache hit ratio

select sum(GETS-GETMISSES)/sum(GETS)*100 "dictionary cahe ration"
from v$rowcache;

To find out Buffer cache hit ratio

select (1-(PHYSICAL_READS/(DB_BLOCK_GETS+CONSISTENT_GETS)))*100 "Buffer cache hit ratio"
from v$buffer_pool_statistics;