REM  #*****************************************************
REM  # File Name: buffer_cache.sql
REM  #
REM  # Purpose: Report the buffer cache hit ratio
REM  #
REM  #*****************************************************

select round(((1-(sum(decode(name,'physical reads',value,0))/ 
       (sum(decode(name,'db block gets',value,0))+
       (sum(decode(name,'consistent gets',value,0))))))
	*100),4) || '%' "Buffer Cache Hit Ratio" 
from v$sysstat;