oracle 中如何定位重要(消耗资源多)的SQL
发表于 2011 年 2 月 17 日 由 惜分飞联系：手机/微信(+86 13429648788) QQ(107644445)
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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(select address,
disk_reads,
executions,
pct,
rank()over(order by disk_reads desc) ranking
from(select address,
disk_reads,
executions,
100*ratio_to_report(disk_reads)over() pct
from sys.v_$sql
where command_type!=47)
where disk_reads>50*executions) s,
sys.v_$sqltext p
where s.ranking<=5
and p.address=s.address
order by 1, s.address, p.piece;
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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
from v$sqlarea a, dba_users b
where a.parsing_user_id = b.user_id
and a.disk_reads > 10000
order by disk_reads desc;
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3、查看逻辑读多的SQL
select*
from(select buffer_gets, sql_text
from v$sqlarea
where buffer_gets>500000
order by buffer_gets desc)
where rownum<=30;
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4、查看执行次数多的SQL
select sql_text, executions
from (select sql_text, executions from v$sqlarea order by executions desc)
where rownum < 81;
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5、查看读硬盘多的SQL
select sql_text, disk_reads
from(select sql_text, disk_reads from v$sqlarea order by disk_reads desc)
where rownum<21;
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6、查看排序多的SQL
select sql_text, sorts
from(select sql_text, sorts from v$sqlarea order by sorts desc)
where rownum<21;
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7、分析的次数太多，执行的次数太少，要用绑变量的方法来写sql
select substr(sql_text, 1, 80) "sql", count(*), sum(executions) "totexecs"
from v$sqlarea
where executions < 5
group by substr(sql_text, 1, 80)
having count(*) > 30
order by 2;
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