oracle 识别’低效执行’的SQL语句

用下列SQL工具找出低效SQL:

 SELECT EXECUTIONS , DISK_READS, BUFFER_GETS,

        ROUND((BUFFER_GETS-DISK_READS)/BUFFER_GETS,2) Hit_radio,

        ROUND(DISK_READS/EXECUTIONS,2) Reads_per_run,

        SQL_TEXT

FROM   V$SQLAREA

WHERE  EXECUTIONS>0

AND     BUFFER_GETS > 0

AND (BUFFER_GETS-DISK_READS)/BUFFER_GETS < 0.8

ORDER BY 4 DESC;

     ( 虽然目前各种关于SQL优化的图形化工具层出不穷,但是写出自己的SQL工具来解决问题始终是一个最好的方法)