ORACLE：使用 LEFT JOIN 时物化视图不起作用

Posted 2023-02-24

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【中文标题】ORACLE：使用 LEFT JOIN 时物化视图不起作用【英文标题】：ORACLE : Materialized view not working when Using LEFT JOIN 【发布时间】：2010-11-21 17:30:06 【问题描述】：

我想从 2 个表的 LEFT JOIN 创建一个 MATERIALIZED VIEW。但是以下给了我一个错误：

    SELECT field1 
     FROM table_1 a 
     LEFT JOIN table_2 b 
     ON a.field1=b.field2

ORA-12054: 无法为实体化视图设置 ON COMMIT 刷新属性

但是以下工作：

SELECT field1 
 FROM table_1 a, table_2 b 
 WHERE a.field1=b.field2

有没有人知道为什么会发生这种情况。

感谢帮助

【问题讨论】：

【参考方案1】：

由于这是一篇旧帖子；没有提到完整的解决方案。

WHERE

SELECT

CASE

DECODE

GROUP BY

SUM()

COUNT()

在上面的示例中，如果在 dept id 列的部门表上创建主键，则查询将起作用。

【讨论】：

“WHERE 子句中不应该有任何过滤条件，只有连接” 你能支持这一点吗？【参考方案2】：

要使物化视图快速刷新，有两个条件不满足。第一个是您没有指定所涉及的每个表的 rowid 列。第二个是未记录的限制：不支持 ANSI 连接。

这是一个示例，DEPT 为 table_1，别名 a，EMP 为 table_2，别名 b：

SQL> create materialized view log on emp with rowid
  2  /

Materialized view log created.

SQL> create materialized view log on dept with rowid
  2  /

Materialized view log created.

SQL> create materialized view empdept_mv
  2    refresh fast on commit
  3  as
  4  select a.deptno
  5    from dept a
  6         left join emp b on (a.deptno = b.deptno)
  7  /
  from dept a
       *
ERROR at line 5:
ORA-12054: cannot set the ON COMMIT refresh attribute for the materialized view

这模仿了你的情况。首先添加rowid的：

SQL> create materialized view empdept_mv
  2    refresh fast on commit
  3  as
  4  select a.rowid dept_rowid
  5       , b.rowid emp_rowid
  6       , a.deptno
  7    from dept a
  8         left join emp b on (a.deptno = b.deptno)
  9  /
  from dept a
       *
ERROR at line 7:
ORA-12054: cannot set the ON COMMIT refresh attribute for the materialized view

由于 ANSI 连接，它仍然无法快速刷新。转换为旧式外连接语法：

SQL> create materialized view empdept_mv
  2    refresh fast on commit
  3  as
  4  select a.rowid dept_rowid
  5       , b.rowid emp_rowid
  6       , a.deptno
  7    from dept a
  8       , emp b
  9   where a.deptno = b.deptno (+)
 10  /

Materialized view created.

并证明它有效：

SQL> select * from empdept_mv
  2  /

DEPT_ROWID         EMP_ROWID              DEPTNO
------------------ ------------------ ----------
AAARhmAAEAAAAI/AAB AAARhlAAEAAAAI3AAA         20
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAB         30
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAC         30
AAARhmAAEAAAAI/AAB AAARhlAAEAAAAI3AAD         20
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAE         30
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAF         30
AAARhmAAEAAAAI/AAA AAARhlAAEAAAAI3AAG         10
AAARhmAAEAAAAI/AAB AAARhlAAEAAAAI3AAH         20
AAARhmAAEAAAAI/AAA AAARhlAAEAAAAI3AAI         10
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAJ         30
AAARhmAAEAAAAI/AAB AAARhlAAEAAAAI3AAK         20
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAL         30
AAARhmAAEAAAAI/AAB AAARhlAAEAAAAI3AAM         20
AAARhmAAEAAAAI/AAA AAARhlAAEAAAAI3AAN         10
AAARhmAAEAAAAI/AAD                            40

15 rows selected.

SQL> insert into dept values (50,'IT','UTRECHT')
  2  /

1 row created.

SQL> commit
  2  /

Commit complete.

SQL> select * from empdept_mv
  2  /

DEPT_ROWID         EMP_ROWID              DEPTNO
------------------ ------------------ ----------
AAARhmAAEAAAAI/AAB AAARhlAAEAAAAI3AAA         20
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAB         30
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAC         30
AAARhmAAEAAAAI/AAB AAARhlAAEAAAAI3AAD         20
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAE         30
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAF         30
AAARhmAAEAAAAI/AAA AAARhlAAEAAAAI3AAG         10
AAARhmAAEAAAAI/AAB AAARhlAAEAAAAI3AAH         20
AAARhmAAEAAAAI/AAA AAARhlAAEAAAAI3AAI         10
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAJ         30
AAARhmAAEAAAAI/AAB AAARhlAAEAAAAI3AAK         20
AAARhmAAEAAAAI/AAC AAARhlAAEAAAAI3AAL         30
AAARhmAAEAAAAI/AAB AAARhlAAEAAAAI3AAM         20
AAARhmAAEAAAAI/AAA AAARhlAAEAAAAI3AAN         10
AAARhmAAEAAAAI/AAD                            40
AAARhmAAEAAAAI7AAA                            50

16 rows selected.

this blogpost 的第 6 点提到了 ANSI 连接语法限制。

问候，抢。

【讨论】：

非常感谢罗。这非常有帮助:) 虽然我必须使用旧样式进行左连接（将不得不重写许多视图和查询），但这让我很恼火。丹不敢相信 Oracle 还没有实现 ANSI JOIN 支持。谢谢你【参考方案3】：

按照以下说明使 DBMS_MVIEW.EXPLAIN_MVIEW 工作： http://www.sqlsnippets.com/en/topic-12884.html

能够：

REFRESH_COMPLETE

没有能力：

REFRESH_FAST

REFRESH_FAST_AFTER_INSERT 此类型 MV 不支持 FROM 列表中的内联视图或子查询

REFRESH_FAST_AFTER_INSERT 从列表中查看或子查询

REFRESH_FAST_AFTER_ONETAB_DML 查看 REFRESH_FAST_AFTER_INSERT 被禁用的原因