ORACLE如何查找运行系统里可能有问题的sql

 

 

 

 

查找bad sql的方法:

select * from 

(select buffer_gets, sql_text from v$sqlarea where buffer_gets >500000 order by buffer_gets desc) 

where rownum<=10;

执行次数多的SQL：

select sql_text,executions from 

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

where rownum<10;

 

读硬盘多的SQL：

select sql_text,disk_reads from 

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

where rownum<10;

 

排序多的SQL：

select sql_text,sorts from 

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

where rownum<10;

 

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:

set pagesize 600; set linesize 1000; 

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

from v$sqlarea 

where executions < 5 

group by substr(sql_text,1,80) having count(*) > 30 

order by 2;

游标的观察：

set pages 100; 

select sum(a.value), b.name 

from v$sesstat a, v$statname b 

where a.statistic# = b.statistic# and b.name = 'opened cursors current' 

group by b.name; 

select count(0) from v$open_cursor; 

select user_name,sql_text,count(0) from v$open_cursor 

group by user_name,sql_text having count(0)>40;

 

查看当前用户&username执行的SQL：

select sql_text 

from v$sqltext_with_newlines 

where (hash_value,address) in 

(select sql_hash_value,sql_address from v$session where username='&username') 

order by address,piece;