Oracle Materialized Views Containing Joins Only

介绍

只包含表连接而没有聚合的物化视图。与聚合类似，表连接也是相当消耗资源的操作，将其结果预先计算并存储于物化视图中，可以提高SQL执行效率。

每一个基表(包括inline view)的Rowid必须出现在物化视图的select部分。这也是该物化视图可以快速刷新的必要条件之一。其他条件包括：

From 语句后的所有表必须建立MV log，且包含rowid

不可包含group by或其他聚合函数

Select语句中不能包含object类型的列

下面是一个例子：

CREATE MATERIALIZED VIEW LOG ON sales WITHROWID;

CREATE MATERIALIZED VIEW LOG ON times WITHROWID;

CREATE MATERIALIZED VIEW detail_sales_mv

BUILD IMMEDIATE

REFRESH FAST ON DEMAND

ENABLE QUERY REWRITE

AS

SELECT s.ROWID sales_rid, t.ROWIDtimes_rid, s.time_id, t.day_name, s.amount_sold, s.quantity_sold

FROM times t , sales s WHERE t.time_id =s.time_id;

同样DDL语句，用inner join就会出现ORA-12015错误

Error starting at line 14 in command:

CREATE MATERIALIZED VIEW detail_sales_mv

BUILD IMMEDIATE

REFRESH FAST ON DEMAND

ENABLE QUERY REWRITE

AS

SELECT s.ROWID sales_rid, t.ROWIDtimes_rid, s.time_id,t.day_name, s.amount_sold, s.quantity_sold

FROM times t INNER JOIN sales s ONt.time_id = s.time_id(+)

Error at Command Line:20 Column:6

Error report:

SQL Error: ORA-12015: cannot create a fastrefresh materialized view from a complex query

12015. 00000 -"cannot create a fast refreshmaterialized view from a complex query"

*Cause:Neither ROWIDs and nor primary key constraints are supported for

complex queries.

*Action:Reissue the command with the REFRESH FORCE or REFRESH COMPLETE

option or create a simple materialized view.

数据库版本：

BANNER

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Oracle Database 11g Enterprise EditionRelease 11.2.0.1.0 - 64bit Production

PL/SQL Release 11.2.0.1.0 - Production

CORE11.2.0.1.0Production

TNS for Linux: Version 11.2.0.1.0 -Production

NLSRTL Version 11.2.0.1.0 - Production

Elapsed: 00:00:00.01

Linux服务器信息：

SQL> !uname -a

Linux odilab 2.6.39-400.17.1.el6uek.x86_64#1 SMP Fri Feb 22 18:16:18 PST 2013 x86_64 x86_64 x86_64 GNU/Linux