Oracle 캐시 적중률 측정

SELECT 1 - (phy.value - lob.value - dir.value)
/ ses.value  "CACHE HIT RATIO"
    FROM   v$sysstat ses, v$sysstat lob,
           v$sysstat dir, v$sysstat phy
    WHERE  ses.name = 'session logical reads'
    AND    dir.name = 'physical reads direct'
    AND    lob.name = 'physical reads direct (lob)'
    AND    phy.name = 'physical reads'
/