背景

在我们维护数据库库过程中，经常会碰到数据库调优的问题。而cpu利用率高是我们最常见的一个问题，而找出哪些session和和SQL语句在消耗最多的CPU，是我们经常面对的一个课题。本文分享一下在ORACLE中如何找出消耗CPU最多的SQL语句。

解决方案

Oracle 中的前 10 个 CPU 消耗会话

col program form a30 heading "Program"
col CPUMins form 99990 heading "CPU in Mins"
select rownum as rank, a.*
from (
SELECT v.sid,sess.Serial# ,program, v.value / (100 * 60) CPUMins
FROM v$statname s , v$sesstat v, v$session sess
WHERE s.name = 'CPU used by this session'
and sess.sid = v.sid
and v.statistic#=s.statistic#
and v.value>0
ORDER BY v.value DESC) a
where rownum < 11;

最近 10 分钟内 CPU 消耗最高的会话

col program form a30 heading "Program"
col CPUMins form 99990 heading "CPU in Mins"
select rownum as rank, a.*
from (
SELECT v.sid,sess.Serial# ,program, v.value / (100 * 60) CPUMins
FROM v$statname s , v$sesstat v, v$session sess
WHERE s.name = 'CPU used by this session'
and sess.sid = v.sid
and v.statistic#=s.statistic#
and v.value>0
ORDER BY v.value DESC) a
where rownum < 11;

在 Oracle 中消耗更多的 CPU的SQL id

col program form a30 heading "Program"
col cpu_usage_sec form 99990 heading "CPU in Seconds"
col MODULE for a18
col OSUSER for a10
col USERNAME for a15
col OSPID for a06 heading "OS PID"
col SID for 99999
col SERIAL# for 999999
col SQL_ID for a15
select * from (
select p.spid "ospid",
(se.SID),ss.serial#,ss.SQL_ID,ss.username,substr(ss.program,1,30) "program",
ss.module,ss.osuser,ss.MACHINE,ss.status,
se.VALUE/100 cpu_usage_sec
from v$session ss,v$sesstat se,
v$statname sn,v$process p
where
se.STATISTIC# = sn.STATISTIC#
and NAME like '%CPU used by this session%'
and se.SID = ss.SID
and ss.username !='SYS'
and ss.status='ACTIVE'
and ss.username is not null
and ss.paddr=p.addr and value > 0
order by se.VALUE desc);

在 Oracle 中最消耗 CPU的SQL 文本

col cpu_usage_sec form 99990 heading "CPU in Seconds"
select * from (
select
(se.SID),substr(q.sql_text,80),ss.module,ss.status,se.VALUE/100 cpu_usage_sec
from v$session ss,v$sesstat se,
v$statname sn, v$process p, v$sql q
where
se.STATISTIC# = sn.STATISTIC#
AND ss.sql_address = q.address
AND ss.sql_hash_value = q.hash_value
and NAME like '%CPU used by this session%'
and se.SID = ss.SID
and ss.username !='SYS'
and ss.status='ACTIVE'
and ss.username is not null
and ss.paddr=p.addr and value > 0
order by se.VALUE desc);