no_expand优化案例
bond 来看一个烂语句：
select a.*,b.dn from temp_allcrmuser a, phs_smc_user b
where a.USERNUMBER=b.dn
and (a.ACTFLAG<>b.ACT_FLG
or a.ENABLEFLAG<>b.ENABLE_FLG);
汽水 15:50:29
但是对你自己做实验，搞工作极其有利
bond15:50:34
-------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 2 | 112 | 12 (17)| 00:00:01 |
| 1 | CONCATENATION | | | | | |
| 2 | MERGE JOIN | | 1 | 56 | 6 (17)| 00:00:01 |
| 3 | TABLE ACCESS BY INDEX ROWID| PHS_SMC_USER | 22 | 396 | 3 (0)| 00:00:01 |
| 4 | INDEX FULL SCAN | IND_SMC_USER_DN | 22 | | 1 (0)| 00:00:01 |
|* 5 | FILTER | | | | | |
|* 6 | SORT JOIN | | 82 | 3116 | 3 (34)| 00:00:01 |
| 7 | TABLE ACCESS FULL | TEMP_ALLCRMUSER | 82 | 3116 | 2 (0)| 00:00:01 |
| 8 | MERGE JOIN | | 1 | 56 | 6 (17)| 00:00:01 |
| 9 | TABLE ACCESS BY INDEX ROWID| PHS_SMC_USER | 22 | 396 | 3 (0)| 00:00:01 |
| 10 | INDEX FULL SCAN | IND_SMC_USER_DN | 22 | | 1 (0)| 00:00:01 |
|* 11 | FILTER | | | | | |
|* 12 | SORT JOIN | | 82 | 3116 | 3 (34)| 00:00:01 |
| 13 | TABLE ACCESS FULL | TEMP_ALLCRMUSER | 82 | 3116 | 2 (0)| 00:00:01 |
-------------------------------------------------------------------------------------------------
bond(510330025) 15:50:48
5 - filter("A"."ENABLEFLAG"<>"B"."ENABLE_FLG")
6 - access("A"."USERNUMBER"="B"."DN")
filter("A"."USERNUMBER"="B"."DN")
11 - filter("A"."ACTFLAG"<>"B"."ACT_FLG" AND LNNVL("A"."ENABLEFLAG"<>"B"."ENABLE_FLG"))
12 - access("A"."USERNUMBER"="B"."DN")
filter("A"."USERNUMBER"="B"."DN")
SELECT *
FROM (SELECT rownum,
a.owner AS owner_a,
b.owner AS owner_b,
a.object_id AS object_id_a,
b.object_id AS object_id_b,
a.object_name
FROM test1 a
INNER JOIN test2 b
ON b.object_name = a.object_name)
WHERE (owner_a <> owner_b OR object_id_a <> object_id_b)
重庆-有教无类16:23:11
这个它改不了了
重庆-有教无类 16:26:13
咋样
重庆-有教无类16:26:17
还con不
bond 16:27:17
==
bond 16:30:59
select * from
(
select rownum a_rownum,a.ACTFLAG a_ACTFLAG,a.ENABLEFLAG a_ENABLEFLAG,b.dn,b.ACT_FLG b_ACT_FLG,b.ENABLE_FLG b_ENABLE_FLG
from temp_allcrmuser a
join phs_smc_user b
on a.USERNUMBER=b.dn) t
where (a_ACTFLAG<>b_ACT_FLG or a_ENABLEFLAG<>b_ENABLE_FLG);
----------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
----------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 22 | 1694 | 8740 (6)| 00:01:45 |
|* 1 | VIEW | | 22 | 1694 | 8740 (6)| 00:01:45 |
| 2 | COUNT | | | | | |
|* 3 | HASH JOIN | | 22 | 1232 | 8740 (6)| 00:01:45 |
| 4 | TABLE ACCESS FULL| PHS_SMC_USER | 22 | 396 | 12 (0)| 00:00:01 |
| 5 | TABLE ACCESS FULL| TEMP_ALLCRMUSER | 10M| 394M| 8571 (4)| 00:01:43 |
--------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("A_ACTFLAG"<>"B_ACT_FLG" OR "A_ENABLEFLAG"<>"B_ENABLE_FLG")
3 - access("A"."USERNUMBER"="B"."DN")
bond 16:31:05
靠，可以了
bond 16:31:18
就是因为rownum？
史狮16:31:22
太牛b
。。。。。省略。。。。。
select /*+ Use_hash(a,b) no_expand*/ a.*,b.dn from temp_allcrmuser a, phs_smc_user b
where a.USERNUMBER=b.dn
and (a.ACTFLAG<>b.ACT_FLG
or a.ENABLEFLAG<>b.ENABLE_FLG);
--------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 18 | 1008 | 8740 (6)| 00:01:45 |
|* 1 | HASH JOIN | | 18 | 1008 | 8740 (6)| 00:01:45 |
| 2 | TABLE ACCESS FULL| PHS_SMC_USER | 22 | 396 | 12 (0)| 00:00:01 |
| 3 | TABLE ACCESS FULL| TEMP_ALLCRMUSER | 10M| 394M| 8571 (4)| 00:01:43 |
--------------------------------------------------------------------------------------
用no_expand HINT也可以
在ORACLE11g 之前，CBO 还是会犯SB ，11g之后 不会自动的 expand了，
注意，上面都是我的学生