ITPub博客
首页 博客 专栏 学院 社区 IT新媒体评选
发博

首页 > Linux操作系统 > Linux操作系统 > 11GR2中RBO执行全外连接结果错误

11GR2中RBO执行全外连接结果错误

原创 Linux操作系统 作者：yangtingkun 时间：2010-10-17 22:30:33 0 删除 编辑

意外发现11.2中，如果在RBO下运行全外连接，会得到错误的结果。

 

 

正常情况下：

SQL> SELECT * FROM V$VERSION;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production

SQL> SET AUTOT ON
SQL> SELECT T1.ID, T2.ID
  2  FROM T1 FULL OUTER JOIN T2
  3  ON T1.ID = T2.ID;

        ID         ID
---------- ----------
         2          2
         3          3
         4          4
         5          5
         6          6
         7          7
         8          8
                    9
                   10
         1
         0

已选择11行。


执行计划
----------------------------------------------------------
Plan hash value: 53297166

----------------------------------------------------------------------------------
| Id  | Operation             | Name     | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------
|   0 | SELECT STATEMENT      |          |     9 |   234 |     9  (12)| 00:00:01 |
|   1 |  VIEW                 | VW_FOJ_0 |     9 |   234 |     9  (12)| 00:00:01 |
|*  2 |   HASH JOIN FULL OUTER|          |     9 |   234 |     9  (12)| 00:00:01 |
|   3 |    TABLE ACCESS FULL  | T1       |     9 |   117 |     4   (0)| 00:00:01 |
|   4 |    TABLE ACCESS FULL  | T2       |     9 |   117 |     4   (0)| 00:00:01 |
----------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - access("T1"."ID"="T2"."ID")

Note
-----
   - dynamic sampling used for this statement (level=2)


统计信息
----------------------------------------------------------
          0  recursive calls
          0  db block gets
         15  consistent gets
          0  physical reads
          0  redo size
        733  bytes sent via SQL*Net to client
        520  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
         11  rows processed

不管优化器是CHOOSE还是RULE，只要是RBO模式，无论是执行计划还是最终查询结果都是错误的：

SQL> ALTER SESSION SET OPTIMIZER_MODE = RULE;

会话已更改。

SQL> SELECT T1.ID, T2.ID
  2  FROM T1 FULL OUTER JOIN T2
  3  ON T1.ID = T2.ID;

        ID         ID
---------- ----------
         2          2
         3          3
         4          4
         5          5
         6          6
         7          7
         8          8

已选择7行。


执行计划
----------------------------------------------------------
Plan hash value: 3374424389

-----------------------------------------
| Id  | Operation            | Name     |
-----------------------------------------
|   0 | SELECT STATEMENT     |          |
|   1 |  VIEW                | VW_FOJ_0 |
|   2 |   MERGE JOIN         |          |
|   3 |    SORT JOIN         |          |
|   4 |     TABLE ACCESS FULL| T2       |
|*  5 |    SORT JOIN         |          |
|   6 |     TABLE ACCESS FULL| T1       |
-----------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   5 - access("T1"."ID"="T2"."ID")
       filter("T1"."ID"="T2"."ID")

Note
-----
   - rule based optimizer used (consider using cbo)


统计信息
----------------------------------------------------------
          1  recursive calls
          0  db block gets
         14  consistent gets
          0  physical reads
          0  redo size
        700  bytes sent via SQL*Net to client
        520  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          2  sorts (memory)
          0  sorts (disk)
          7  rows processed

SQL> ALTER SESSION SET OPTIMIZER_MODE = CHOOSE;                 

会话已更改。

SQL> SELECT T1.ID, T2.ID
  2  FROM T1 FULL OUTER JOIN T2
  3  ON T1.ID = T2.ID;

        ID         ID
---------- ----------
         2          2
         3          3
         4          4
         5          5
         6          6
         7          7
         8          8

已选择7行。


执行计划
----------------------------------------------------------
Plan hash value: 3374424389

-----------------------------------------
| Id  | Operation            | Name     |
-----------------------------------------
|   0 | SELECT STATEMENT     |          |
|   1 |  VIEW                | VW_FOJ_0 |
|   2 |   MERGE JOIN         |          |
|   3 |    SORT JOIN         |          |
|   4 |     TABLE ACCESS FULL| T2       |
|*  5 |    SORT JOIN         |          |
|   6 |     TABLE ACCESS FULL| T1       |
-----------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   5 - access("T1"."ID"="T2"."ID")
       filter("T1"."ID"="T2"."ID")

Note
-----
   - rule based optimizer used (consider using cbo)


统计信息
----------------------------------------------------------
          1  recursive calls
          0  db block gets
         14  consistent gets
          0  physical reads
          0  redo size
        700  bytes sent via SQL*Net to client
        520  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          2  sorts (memory)
          0  sorts (disk)
          7  rows processed

而这个错误在10g中不会出现：

SQL> SELECT * FROM V$VERSION;

BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bi
PL/SQL Release 10.2.0.3.0 - Production
CORE    10.2.0.3.0      Production
TNS for Linux: Version 10.2.0.3.0 - Production
NLSRTL Version 10.2.0.3.0 - Production

SQL> CREATE TABLE T1 (ID NUMBER, NAME VARCHAR2(30));

Table created.

SQL> CREATE TABLE T2 (ID NUMBER, NAME VARCHAR2(30));

Table created.

SQL> INSERT INTO T1
  2  SELECT ROWNUM - 1, OBJECT_NAME
  3  FROM USER_OBJECTS
  4  WHERE ROWNUM < 10;

9 rows created.

SQL> INSERT INTO T2
  2  SELECT ROWNUM + 1, OBJECT_NAME
  3  FROM USER_OBJECTS
  4  WHERE ROWNUM < 10;

9 rows created.

SQL> SET AUTOT ON
SQL> SELECT T1.ID, T2.ID
  2  FROM T1 FULL OUTER JOIN T2
  3  ON T1.ID = T2.ID;

        ID         ID
---------- ----------
         2          2
         3          3
         4          4
         5          5
         6          6
         7          7
         8          8
         1
         0
                   10
                    9

11 rows selected.


Execution Plan
----------------------------------------------------------
Plan hash value: 2841162349

-----------------------------------------------------------------------------
| Id  | Operation            | Name | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------
|   0 | SELECT STATEMENT     |      |    10 |   260 |    13   (8)| 00:00:01 |
|   1 |  VIEW                |      |    10 |   260 |    13   (8)| 00:00:01 |
|   2 |   UNION-ALL          |      |       |       |            |          |
|*  3 |    HASH JOIN OUTER   |      |     9 |   234 |     7  (15)| 00:00:01 |
|   4 |     TABLE ACCESS FULL| T1   |     9 |   117 |     3   (0)| 00:00:01 |
|   5 |     TABLE ACCESS FULL| T2   |     9 |   117 |     3   (0)| 00:00:01 |
|*  6 |    HASH JOIN ANTI    |      |     1 |    26 |     7  (15)| 00:00:01 |
|   7 |     TABLE ACCESS FULL| T2   |     9 |   117 |     3   (0)| 00:00:01 |
|   8 |     TABLE ACCESS FULL| T1   |     9 |   117 |     3   (0)| 00:00:01 |
-----------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   3 - access("T1"."ID"="T2"."ID"(+))
   6 - access("T1"."ID"="T2"."ID")

Note
-----
   - dynamic sampling used for this statement


Statistics
----------------------------------------------------------
         15  recursive calls
          0  db block gets
         61  consistent gets
          0  physical reads
          0  redo size
        718  bytes sent via SQL*Net to client
        492  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          4  sorts (memory)
          0  sorts (disk)
         11  rows processed

SQL> ALTER SESSION SET OPTIMIZER_MODE = RULE;

Session altered.

SQL> SELECT T1.ID, T2.ID
  2  FROM T1 FULL OUTER JOIN T2
  3  ON T1.ID = T2.ID;

        ID         ID
---------- ----------
         2          2
         3          3
         4          4
         5          5
         6          6
         7          7
         8          8
         1
         0
                   10
                    9

11 rows selected.


Execution Plan
----------------------------------------------------------
Plan hash value: 2841162349

-----------------------------------------------------------------------------
| Id  | Operation            | Name | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------
|   0 | SELECT STATEMENT     |      |    10 |   260 |    13   (8)| 00:00:01 |
|   1 |  VIEW                |      |    10 |   260 |    13   (8)| 00:00:01 |
|   2 |   UNION-ALL          |      |       |       |            |          |
|*  3 |    HASH JOIN OUTER   |      |     9 |   234 |     7  (15)| 00:00:01 |
|   4 |     TABLE ACCESS FULL| T1   |     9 |   117 |     3   (0)| 00:00:01 |
|   5 |     TABLE ACCESS FULL| T2   |     9 |   117 |     3   (0)| 00:00:01 |
|*  6 |    HASH JOIN ANTI    |      |     1 |    26 |     7  (15)| 00:00:01 |
|   7 |     TABLE ACCESS FULL| T2   |     9 |   117 |     3   (0)| 00:00:01 |
|   8 |     TABLE ACCESS FULL| T1   |     9 |   117 |     3   (0)| 00:00:01 |
-----------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   3 - access("T1"."ID"="T2"."ID"(+))
   6 - access("T1"."ID"="T2"."ID")

Note
-----
   - dynamic sampling used for this statement


Statistics
----------------------------------------------------------
         13  recursive calls
          0  db block gets
         61  consistent gets
          0  physical reads
          0  redo size
        718  bytes sent via SQL*Net to client
        492  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          4  sorts (memory)
          0  sorts (disk)
         11  rows processed

SQL> SELECT /*+ RULE */ T1.ID, T2.ID
  2  FROM T1 FULL OUTER JOIN T2
  3  ON T1.ID = T2.ID;

        ID         ID
---------- ----------
         2          2
         3          3
         4          4
         5          5
         6          6
         7          7
         8          8
         1
         0
                   10
                    9

11 rows selected.


Execution Plan
----------------------------------------------------------
Plan hash value: 2841162349

-----------------------------------------------------------------------------
| Id  | Operation            | Name | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------
|   0 | SELECT STATEMENT     |      |    10 |   260 |    13   (8)| 00:00:01 |
|   1 |  VIEW                |      |    10 |   260 |    13   (8)| 00:00:01 |
|   2 |   UNION-ALL          |      |       |       |            |          |
|*  3 |    HASH JOIN OUTER   |      |     9 |   234 |     7  (15)| 00:00:01 |
|   4 |     TABLE ACCESS FULL| T1   |     9 |   117 |     3   (0)| 00:00:01 |
|   5 |     TABLE ACCESS FULL| T2   |     9 |   117 |     3   (0)| 00:00:01 |
|*  6 |    HASH JOIN ANTI    |      |     1 |    26 |     7  (15)| 00:00:01 |
|   7 |     TABLE ACCESS FULL| T2   |     9 |   117 |     3   (0)| 00:00:01 |
|   8 |     TABLE ACCESS FULL| T1   |     9 |   117 |     3   (0)| 00:00:01 |
-----------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   3 - access("T1"."ID"="T2"."ID"(+))
   6 - access("T1"."ID"="T2"."ID")

Note
-----
   - dynamic sampling used for this statement


Statistics
----------------------------------------------------------
         13  recursive calls
          0  db block gets
         61  consistent gets
          0  physical reads
          0  redo size
        718  bytes sent via SQL*Net to client
        492  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          4  sorts (memory)
          0  sorts (disk)
         11  rows processed

虽然10g中Oracle根本不会选择在RBO下执行全外连接，不过起码保证查询结果的正确性，不知道为什么10g中不存在的错误在11g的RBO反倒出现了，理论上讲11g的RBO应该没有再做什么修改才对。

 

来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/4227/viewspace-676142/ ，如需转载，请注明出处，否则将追究法律责任。

0
0
上一篇： ROLE启用个数限制
下一篇： 多源复制案例——流
请登录后发表评论 登录
全部评论
yangtingkun
暂无介绍

注册时间：2007-12-29

  • 博文量
    1964
  • 访问量
    11076925

最新文章

支持我们 作者招募 用户协议 FAQ Contact Us 编辑准则

北京盛拓优讯信息技术有限公司. 版权所有  京ICP备16024965号-8 北京市公安局海淀分局网监中心备案编号：11010802021510 niuxiaotong@pcpop.com 17352615567 未成年人举报专区

广播电视节目制作经营许可证(京) 字第1234号 中国互联网协会会员

违法和不良信息举报电话:18101376593