1、查看Oracle数据库缓冲区命中率
select a.value + b.value "logical_reads", c.value "phys_reads", round(100 * ((a.value+b.value)-c.value) / (a.value+b.value)) "BUFFER HIT RATIO" from v$sysstat a, v$sysstat b, v$sysstat c where a.statistic# = 40 and b.statistic# = 41 and c.statistic# = 42 2、Tags: oracle 数据库缓冲区命中率： sql>select value from v$sysstat where name ='physical reads'; value 3714179 sql>select value from v$sysstat where name ='physical reads direct'; value 0 sql>select value from v$sysstat where name ='physical reads direct(lob)'; value 0 sql>select value from v$sysstat where name ='consistent gets'; value 856309623 sql>select value from v$sysstat where name ='db block gets'; value 19847790 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%，则应该调整应用可以考虑是否增大数据加 共享池的命中率 sql> select sum(pinhits)/sum(pins)*100 "hit radio" from v$librarycache; 如果共享池的命中率低于95％就要考虑调整应用（通常是没应用bind var)或者增加内存。 关于排序部分 sql> select name,value from v$sysstat where name like '%sort%'; 如果我们发现sorts(disk)/(sorts(memory)+sorts(disk))的比例过高，则通常意味着sort_area_size部分内存教较小，可考虑调整相应的参数。 关于log_buffer sql>select name,value from v$sysstat where name in ('redo entries','redo buffer allocation retries'); 假如redo buffer allocation retries/redo entries的比例超过1%我们就可以考虑增加log_buffer.