REM Checks database buffer hit ratio:
REM Hit Ratio= ( 1- (physical-reads/(db-block-gets+consistent-gets) ) )
spool buffer
select s1.value "Db block gets",
s2.value "Consistent gets",
s3.value "Physical reads",
round(100*(1-(s3.value/(s1.value+s2.value)))) "hit %"
from v$sysstat s1, v$sysstat s2, v$sysstat s3
where s1.name='db block gets'
and s2.name='consistent gets'
and s3.name='physical reads'
/