数据高速缓存区命中率计算公式：1(physical reads / (db block gets + consistent gets))命中率应大于0.90最好select name,valuefrom v$sysstatwhere name in (''physical reads'',''db block gets'',''consistent gets'')/共享区库缓存区命中率计算公式：SUM(pins reloads) / SU