前几天,一个用户研发QQ找我,如下: 自由的海豚。 16:12:01 岛主,我的一条SQL查不出来结果,能帮我看看不? 兰花岛主 16:12:10 多久不出结果? 自由的海豚 16:12:17 多久都没出结果,一直没看到结果过。 兰花岛主 16:12:26 呵呵,好。 兰花岛主 16:12:39
前几天,一个用户研发QQ找我,如下:
自由的海豚。 16:12:01
岛主,我的一条SQL查不出来结果,能帮我看看不?
兰花岛主 16:12:10
多久不出结果?
自由的海豚 16:12:17
多久都没出结果,一直没看到结果过。
兰花岛主 16:12:26
呵呵,好。
兰花岛主 16:12:39
发下sql和执行计划。
自由的海豚 16:12:55
select n.c1, n.c2,n.c3,n.c4,n.c5
from (select count(t.c1), t.c1, t.c2,t.c3,t.c4,t.c5
from tab1 t
where t.c2 not in ('val1','val2','val3','val4','val5')
group by t.c1, t.c2,t.c3,t.c4,t.c5) n
where not exists
(select * from (
select count(s.c2), s.c1, s.c2
from (select m.c1, m.c2,m.c3,m.c4,m.c5
from tab1 m
where exists (select c1
from tab2 n
where c2 > sysdate - 14
and m.c1 = n.c1)
and m.c1 is not null
and m.c2 not in ('val1','val2', 'val3', 'val4', 'val5')) s
group by s.c1, s.c2) t1 where t1.c2 = n.c2)
and n.c1 is not null;
兰花岛主 16:13:12
这两张表大吗?
自由的海豚 16:13:16
tab1小,tab2亿级以上,两周数据在几千万。
兰化岛主 16:13:22
OK。
兰花岛主 16:16:29
这么改下sql吧:
with t1 as(
select count(t.c1), t.c1,t.c2,t.c3,t.c4,t.c5
from tab1 t
where t.c2 not in ('val1','val2','val3','val4','val5')
and c1 is not null
group by t.c1, t.c2,t.c3,t.c4,t.c5)
select t1.c1,t1.c2,t1.c3,t1.c4,t1.c5
from t1
where not exists(
select /*+ use_hash(m,n)*/ m.c1, m.c2,m.c3,m.c4,m.c5
from t1 m,tab2 n
where n.c2 > sysdate - 14
and m.c1 = n.c1
and t1.c2 = m.c2);
兰花岛主 16:16:43
取下执行计划。
自由的海豚 16:16:57
好的。
自由的海豚 16:17:25
兰花岛主 16:17:57
好的,试试吧。
自由的海豚 16:19:28
出结果了,37s
兰花岛主 17:20:21
嗯,好。
兰花岛主 17:20:34
这样可以吗?
自由的海豚 17:20:47
可以了可以了
兰花岛主 17:21:11
嗯,好,那就先这样,不继续调了。
自由的海豚 17:21:30
恩 好的 谢谢岛主
兰花岛主 17:21:53
不客气,忙吧,有事儿联系。
自由的海豚 17:22:18
恩,您忙。。。
至此,对用户这个sql的优化结束,其实,这个语句应该还有优化的空间,只是,用户说可以了那就可以了,因为优化是无止境的,而且,更进一步优化也许会需要更进一步的信息,且有时会需要更大的改动,鉴于各方面因素,文中对语句和计划进行了处理,记录于此,共勉!

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