概述
It is very easy for us to implement sql tuning by toad. We need to do is just give complex sql statement to toad.
相信很多朋友都会碰到那些几十行几百行的sql,像这种复杂的sql单单去做分析都很耗费我们的时间了，有没有一种办法可以一键优化这种复杂的sql语句呢？今天主要分享一下怎么通过toad工具去优化那些复杂的sql，目的是帮助我们减少优化的时间。
原始sql
SELECT mm.inst_id,
mm.sid,
mm.TYPE,
mm.id1,
mm.id2,
LPAD (TRUNC (mm.ctime / 60 / 60), 3)
|| ‘ Hour ‘
|| LPAD (
TO_CHAR (
TRUNC (mm.ctime / 60) - TRUNC (mm.ctime / 60 / 60) * 60,
‘fm09‘),
2)
|| ‘ Min ‘
|| LPAD (TO_CHAR (mm.ctime - TRUNC (mm.ctime / 60) * 60, ‘fm09‘), 2)
|| ‘ Sec‘
ctime,
CASE
WHEN mm.block = 1 AND mm.lmode != 0 THEN ‘holder‘
WHEN mm.block = 0 AND mm.request != 0 THEN ‘waiter‘
ELSE NULL
END
role,
CASE
WHEN ee.blocking_session IS NOT NULL
THEN
‘waiting for SID ‘ || ee.blocking_session
ELSE
NULL
END
blocking_session,
dd.sql_text sql_text,
cc.event wait_event
FROM gv$lock mm,
gv$session ee,
gv$sqlarea dd,
gv$session_wait cc
WHERE mm.sid IN
(SELECT nn.sid
FROM (SELECT tt.*,
COUNT (1)
OVER (PARTITION BY tt.TYPE, tt.id1, tt.id2)
cnt,
MAX (tt.lmode)
OVER (PARTITION BY tt.TYPE, tt.id1, tt.id2)
lmod_flag,
MAX (tt.request)
OVER (PARTITION BY tt.TYPE, tt.id1, tt.id2)
request_flag
FROM gv$lock tt) nn
WHERE nn.cnt > 1
AND nn.lmod_flag != 0
AND nn.request_flag != 0)
AND mm.sid = ee.sid(+)
AND ee.sql_id = dd.sql_id(+)
AND mm.sid = cc.sid(+)
AND ( (mm.block = 1 AND mm.lmode != 0)
OR (mm.block = 0 AND mm.request != 0))
ORDER BY mm.TYPE,
mm.id1,
mm.id2,
mm.lmode DESC,
mm.ctime DESC
1、Get execution plan
Editor --> Explain plan current SQL or CTRL + E
可以看到执行计划如下：
2、 Get statistics/Auto Trace
开启自动trace跟踪：
或者在sql编辑区右键选择去开启自动跟踪：
3、Get statistics after executed sql.
点击执行后可以看到sql相关统计信息：
4、 Tuning SQL
选择自动优化sql:
执行sql:
可以看到正在自动优化：
优化完成后如下：
5、 Compare result
这里我们可以看到其中一条sql从3.7秒优化到0.04秒
最终sql
SELECT /*+ NO_CPU_COSTING */ mm.inst_id,
mm.sid,
mm.TYPE,
mm.id1,
mm.id2,
LPAD(TRUNC(mm.ctime / 60 / 60), 3) || ‘ Hour ‘ || LPAD(TO_CHAR(TRUNC(mm.ctime / 60) - TRUNC(mm.ctime / 60 / 60) * 60, ‘fm09‘), 2) || ‘ Min ‘ || LPAD(TO_CHAR(mm.ctime - TRUNC(mm.ctime / 60) * 60, ‘fm09‘), 2) || ‘ Sec‘ ctime,
CASE WHEN mm.block = 1
AND mm.lmode != 0 THEN ‘holder‘
WHEN mm.block = 0
AND mm.request != 0 THEN ‘waiter‘
ELSE NULL END role,
CASE WHEN ee.blocking_session IS NOT NULL THEN ‘waiting for SID ‘ || ee.blocking_session
ELSE NULL END blocking_session,
dd.sql_text sql_text,
cc.event wait_event
FROM gv$lock mm,
gv$session ee,
gv$sqlarea dd,
gv$session_wait cc
WHERE EXISTS (SELECT ‘X‘
FROM (SELECT tt.*,
COUNT(1) OVER (PARTITION BY tt.TYPE,
tt.id1,
tt.id2) cnt, MAX(tt.lmode) OVER (PARTITION BY tt.TYPE,
tt.id1,
tt.id2) lmod_flag, MAX(tt.request) OVER (PARTITION BY tt.TYPE,
tt.id1,
tt.id2) request_flag
FROM gv$lock tt) nn
WHERE nn.cnt > 1
AND nn.lmod_flag != 0
AND nn.request_flag != 0
AND nn.sid = mm.sid)
AND mm.sid = ee.sid (+)
AND ee.sql_id = dd.sql_id (+)
AND mm.sid = cc.sid (+)
AND (mm.block = 1
AND mm.lmode <> 0
OR mm.block = 0
AND mm.request <> 0)
ORDER BY mm.TYPE, mm.id1, mm.id2, mm.lmode DESC,
mm.ctime DESC
虽然花上一些时间我们也可以优化到我们想要的结果，但是通过工具去帮助我们减少这些时间，何乐而不为呢？
觉得有用的朋友多帮忙转发哦！后面会分享更多devops和DBA方面的内容，感兴趣的朋友可以关注下~