本篇内容主要讲解“Oracle常用性能分析语句有哪些”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“Oracle常用性能分析语句有哪些”吧!
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1、查看数据库中过去15分钟内排在前5位的等待事件及其总等待时间
select * from ( SELECT NVL(event, 'ON CPU') event, COUNT(*) total_wait_tm FROM v$active_session_history WHERE sample_time > SYSDATE - 15/(24*60) GROUP BY event ORDER BY 2 desc ) where rownum <= 5;
2、查看过去15分钟内使用CPU及资源最多的前5位会话
column username format a12 column module format a30 SELECT * FROM ( SELECT s.username, s.module, s.sid, s.serial#, count(*) FROM v$active_session_history h, v$session s WHERE h.session_id = s.sid AND h.session_serial# = s.serial# AND session_state= 'ON CPU' AND sample_time > sysdate - interval '15' minute GROUP BY s.username, s.module, s.sid, s.serial# ORDER BY count(*) desc ) where rownum <= 5;
session_state列有两个有效的值：ON CPU和WAITING，分别表示会话是活动的还是在等待资源，同样将session_state指定为WAITING值，可以查看在等待资源的前5位会话信息。
3、查看那些业务用户占用最多的资源
SELECT * FROM
(
SELECT u.username, h.module, h.session_id sid,
h.session_serial# serial#, count(*)
FROM dba_hist_active_sess_history h, dba_users u
WHERE h.user_id = u.user_id
AND session_state= 'ON CPU'
AND (sample_time between to_date('2018-07-22:00:00:00','yyyy-mm-dd:hh34:mi:ss')
AND to_date('2018-07-22:23:59:59','yyyy-mm-dd:hh34:mi:ss'))
AND u.username != 'SYS'
GROUP BY u.username, h.module, h.session_id, h.session_serial#
ORDER BY count(*) desc
)
where rownum <= 5;4、定位造成大量资源消耗的对象信息
SELECT * FROM
(
select * from (
SELECT o.object_name, o.object_type, s.event, s.time_waited
FROM dba_hist_active_sess_history s, dba_objects o
WHERE s.sample_time
between to_date('2018-07-22:00:00:00','yyyy-mm-dd:hh34:mi:ss')
AND to_date('2018-07-22:23:59:59','yyyy-mm-dd:hh34:mi:ss')
AND s.current_obj# = o.object_id
ORDER BY 4 desc
)
WHERE rownum <= 5;5、查看过去15分钟内造成最多数据库等待的sql语句
select ash.user_id, u.username, s.sql_text, sum(ash.wait_time + ash.time_waited) ttl_wait_time from v$active_session_history ash, v$sqlarea s, dba_users u where ash.sample_time between sysdate - 15/(24*60) and sysdate and ash.sql_id = s.sql_id and ash.user_id = u.user_id group by ash.user_id,s.sql_text, u.username order by ttl_wait_time
6、找出谁持有阻塞锁
select s1.username || '@' || s1.machine || ' ( SID=' || s1.sid || ' ) is blocking ' || s2.username || '@' || s2.machine || ' ( SID=' || s2.sid || ' ) ' AS blocking_status from v$lock l1, v$session s1, v$lock l2, v$session s2 where s1.sid=l1.sid and s2.sid=l2.sid and l1.BLOCK=1 and l2.request > 0 and l1.id1 = l2.id1 and l2.id2 = l2.id2 ;
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