DBMS_MVIEW.EXPLAIN_MVIEW包的使用

DBMS_MVIEW.EXPLAIN_MVIEW能分析三种不同的物化视图代码，分别是：
1.定义的查询
2.一个CREATE MATERIALIZED VIEW的语句
3.一个存在的物化视图

步骤如下：
1、提前执行dbms_mview.explain_mview用到的表mv_capabilities_table的建表语句
SQL>@F:\oracle\product\10.2.0\db_1\RDBMS\ADMIN\utlxmv.sql;
如果未执行此语句，则有运行包的时候会报表不存在的错误。

2、先清空表中记录，便于分析信息的查看
TRUNCATE TABLE mv_capabilities_table;

3、执行包dbms_mview.explain_mview，其中，包里的参数可以是物化视图、查询语句、
CREATE物化视图语句。
begin
dbms_mview.explain_mview('SELECT a.id,b.name,a.rowid a_rowid,b.rowid b_rowid

   FROM comp1 a , comp2 b WHERE a.id=b.id');
end;
/

4、查看分析结果或错误报告
select MSGTXT from mv_capabilities_table where capability_name='REFRESH_FAST_AFTER_INSERT';
或
select * from mv_capabilities_table;
Tips:
(1)、物化视图在判断是否支持刷新时不支持SQL92的标准外联接的写法，需要改成Oracle自己的(+)的方式。
(2)、对于包含外联接的物化视图的快速刷新，无法高效的利用物化视图日志，因此即使是快速刷新，
性能也可能很差。
 
 
 
 
首先要建表$ORACLE_HOME\RDBMS\ADMIN\utlxmv.sql;
utlxmv.sql的内容如下：

CREATE TABLE MV_CAPABILITIES_TABLE

  (STATEMENT_ID         VARCHAR(30),  -- Client-supplied unique statement identifier

   MVOWNER              VARCHAR(30),  -- NULL for SELECT based EXPLAIN_MVIEW

   MVNAME               VARCHAR(30),  -- NULL for SELECT based EXPLAIN_MVIEW

   CAPABILITY_NAME      VARCHAR(30),  -- A descriptive name of the particular

                                      -- capability:

                                      -- REWRITE

                                      --   Can do at least full text match

                                      --   rewrite

                                      -- REWRITE_PARTIAL_TEXT_MATCH

                                      --   Can do at leat full and partial

                                      --   text match rewrite

                                      -- REWRITE_GENERAL

                                      --   Can do all forms of rewrite

                                      -- REFRESH

                                      --   Can do at least complete refresh

                                      -- REFRESH_FROM_LOG_AFTER_INSERT

                                      --   Can do fast refresh from an mv log

                                      --   or change capture table at least

                                      --   when update operations are

                                      --   restricted to INSERT

                                      -- REFRESH_FROM_LOG_AFTER_ANY

                                      --   can do fast refresh from an mv log

                                      --   or change capture table after any

                                      --   combination of updates

                                      -- PCT

                                      --   Can do Enhanced Update Tracking on

                                      --   the table named in the RELATED_NAME

                                      --   column.  EUT is needed for fast

                                      --   refresh after partitioned

                                      --   maintenance operations on the table

                                      --   named in the RELATED_NAME column

                                      --   and to do non-stale tolerated

                                      --   rewrite when the mv is partially

                                      --   stale with respect to the table

                                      --   named in the RELATED_NAME column.

                                      --   EUT can also sometimes enable fast

                                      --   refresh of updates to the table

                                      --   named in the RELATED_NAME column

                                      --   when fast refresh from an mv log

                                      --   or change capture table is not

                                      --   possilbe.

   POSSIBLE             CHARACTER(1), -- T = capability is possible

                                      -- F = capability is not possible

   RELATED_TEXT         VARCHAR(2000),-- Owner.table.column, alias name, etc.

                                      -- related to this message.  The

                                      -- specific meaning of this column

                                      -- depends on the MSGNO column.  See

                                      -- the documentation for

                                      -- DBMS_MVIEW.EXPLAIN_MVIEW() for details

   RELATED_NUM          NUMBER,       -- When there is a numeric value

                                      -- associated with a row, it goes here.

                                      -- The specific meaning of this column

                                      -- depends on the MSGNO column.  See

                                      -- the documentation for

                                      -- DBMS_MVIEW.EXPLAIN_MVIEW() for details

   MSGNO                INTEGER,      -- When available, QSM message #

                                      -- explaining why not possible or more

                                      -- details when enabled.

   MSGTXT               VARCHAR(2000),-- Text associated with MSGNO.

   SEQ                  NUMBER);     

          -- Useful in ORDER BY clause when

                                      -- selecting from this table.

 

 
1.先建物化视图 。
 CREATE MATERIALIZED VIEW cal_month_sales_mv

 BUILD IMMEDIATE

 REFRESH FORCE

 ENABLE QUERY REWRITE AS

 SELECT t.calendar_month_desc, SUM(s.amount_sold) AS dollars

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

 GROUP BY t.calendar_month_desc;
 
2.执行存储过程包，进行分析。
 EXECUTE DBMS_MVIEW.EXPLAIN_MVIEW ('SH.CAL_MONTH_SALES_MV');
 
3.执行以下语句，查看分析的结果。
 SELECT capability_name, possible, SUBSTR(related_text,1,8)

 AS rel_text, SUBSTR(msgtxt,1,60) AS msgtxt

 FROM MV_CAPABILITIES_TABLE

 ORDER BY seq;