1、数据缓冲区命中率： 
SQL> select value from v$sysstat where name ='physical reads'; 
SQL> select value from v$sysstat where name ='physical reads direct'; 
SQL> select value from v$sysstat where name ='physical reads direct (lob)'; 
SQL> select value from v$sysstat where name ='consistent gets'; 
SQL> select value from v$sysstat where name = 'db block gets'; 
这里命中率的计算应该是 
令 x = physical reads direct + physical reads direct (lob) 
命中率 =100 - ( physical reads - x) / (consistent gets + db block gets - x)*100 
通常如果发现命中率低于90%,则应该调整应用可可以考虑是否增大数据缓冲区 
2、共享池的命中率： 
SQL> select sum(pinhits-reloads)/sum(pins)*100 "hit radio" from v$librarycache; 
假如共享池的命中率低于95%,就要考虑调整应用（通常是没使用bind var ）或者增加内存

本文转自 fish_yy 51CTO博客，原文链接：http://blog.51cto.com/tester2test/138740，如需转载请自行联系原作者