oracle 中如何定位重要(消耗资源多)的SQL

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标题：oracle 中如何定位重要(消耗资源多)的SQL

作者：惜分飞©版权所有[文章允许转载,但必须以链接方式注明源地址,否则追究法律责任.]

1、查看值得怀疑的SQL

select substr(to_char(s.pct,'99.00'),2)||'%'load,

       s.executions executes,

       p.sql_text

from(selectaddress,

               disk_reads,

               executions,

               pct,

               rank()over(orderby disk_reads desc) ranking

         from(selectaddress,

                       disk_reads,

                       executions,

                      100*ratio_to_report(disk_reads)over() pct

                 fromsys.v_$sql

                wherecommand_type!=47)

        wheredisk_reads>50*executions) s,

       sys.v_$sqltext p

where s.ranking<=5

  andp.address=s.address

order by 1, s.address, p.piece;

2、查看消耗内存多的sql

select b.username,

       a. buffer_gets,

       a.executions,

       a.disk_reads / decode(a.executions, 0, 1, a.executions),

       a.sql_text SQL

  fromv$sqlarea a, dba_users b

 wherea.parsing_user_id = b.user_id

   anda.disk_reads > 10000

 orderby disk_reads desc;

3、查看逻辑读多的SQL

select*

from(selectbuffer_gets, sql_text

         fromv$sqlarea

        wherebuffer_gets>500000

        orderby buffer_gets desc)

where rownum<=30;

4、查看执行次数多的SQL

select sql_text, executions

  from(select sql_text, executions from v$sqlarea order by executions desc)

 whererownum < 81;

5、查看读硬盘多的SQL

select sql_text, disk_reads

from(selectsql_text, disk_reads fromv$sqlarea order by disk_reads desc)

where rownum<21;

6、查看排序多的SQL

select sql_text, sorts

from(selectsql_text, sorts fromv$sqlarea order by sorts desc)

where rownum<21;

7、分析的次数太多，执行的次数太少，要用绑变量的方法来写sql

select substr(sql_text, 1, 80) "sql",count(*), sum(executions)"totexecs"

  fromv$sqlarea

 whereexecutions < 5

 groupby substr(sql_text, 1, 80)

having count(*) > 30

 orderby 2;