Oracle性能调优过程中如何观察缓存命中率

在Oracle数据库性能调优的过程中，当需要观察缓存命中率(Measure the Buffer Cache Hit Ratio)时，我们可以使用下面的语句:

rem-------------------------------------------rem 测量缓存命中率rem -------------------------------------------- 获取初始缓存命中率...SELECT ROUND((1-(phy.value / (cur.value + con.value)))*100,2) 'Cache Hit Ratio'FROM v$sysstat cur, v$sysstat con, v$sysstat phyWHERE cur.name = 'db block gets'AND con.name = 'consistent gets'AND phy.name = 'physical reads'/-- 我们人为来增加缓存命中率...DECLAREv_dummy dual.dummy%TYPE;BEGINFOR I IN 1..1000 LOOPSELECT dummy INTO v_dummy FROM dual;END LOOP;END;/-- 我们再来测量...SELECT ROUND((1-(phy.value / (cur.value + con.value)))*100,2) 'Cache Hit Ratio'FROM v$sysstat cur, v$sysstat con, v$sysstat phyWHERE cur.name = 'db block gets'AND con.name = 'consistent gets'AND phy.name = 'physical reads'/