PLSQL_Oracle物化视图Material View的基本概念和用法 （概念）

2014-06-08 Created By BaoXinjian

1. 用法

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物化视图是包括一个查询结果的数据库对象，它是远程数据的的本地副本，或者用来生成基于数据表求和的汇总表。

物化视图存储基于远程表的数据，也可以称为快照。对于复制，物化视图允许你在本地维护远程数据的副本,这些副本是只读的。

如果你想修改本地副本，必须用高级复制的功能。当你想从一个表或视图中抽取数据时，你可以用从物化视图中抽取。

对于数据仓库，创建的物化视图通常情况下是聚合视图，单一表聚合视图和连接视图。    

实现两个数据库之间的数据同步，可以存在时间差。

1. 刷新的方式

Fast

Complete

Fource

2. 刷新的方法

DBMS_REFRESH.Refresh

DBMS_MVIEW.Refresh

 

2. 具体应用

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    (1).在源数据库建立mview log日志文件

        create materialized view log on w_1 ;

----注：(TEST为表名或者视图名，关于视图上建立物化视图，见基于视图的物化视图

----创建物化视图语句：

    (2).在统计数据建立materializad view  语法    

Create materialized view MV_TEST

----MVTEST为物化视图名

Build immediate

----创建时生成数据对应的是build deferred

Refresh fast

----增量刷新

On commit

----在基表有更新时提交，这里该句对视图无效

With rowid

----这里创建基于rowid的物化视图，对应的是 primary key

As

Select * from TEST;

----生成物化视图数据语句

    (3).调用时进行刷新

        dbms_refresh.refresh('W_1')

 

3. 语法

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 1. 基本语法

    

4. 案例

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案例： 创建三种刷新方式的物化视图， 并创建日志，通过dbms_job定时refresh mview group

Step1. 创建三个实体表

CREATE TABLE bxj_objects_t1
(
   owner,
   object_name,
   subobject_name,
   object_id PRIMARY KEY,
   data_object_id,
   object_type,
   created,
   last_ddl_time,
   timestamp,
   status,
   temporary,
   generated,
   secondary,
   namespace,
   edition_name
)
AS
   SELECT   * FROM all_objects;
   
   
CREATE TABLE bxj_objects_t2
(
   owner,
   object_name,
   subobject_name,
   object_id PRIMARY KEY,
   data_object_id,
   object_type,
   created,
   last_ddl_time,
   timestamp,
   status,
   temporary,
   generated,
   secondary,
   namespace,
   edition_name
)
AS
   SELECT   * FROM all_objects;
   
   
CREATE TABLE bxj_objects_t3
(
   owner,
   object_name,
   subobject_name,
   object_id PRIMARY KEY,
   data_object_id,
   object_type,
   created,
   last_ddl_time,
   timestamp,
   status,
   temporary,
   generated,
   secondary,
   namespace,
   edition_name
)
AS
   SELECT   * FROM all_objects;

 

Step2. 创建物化视图日志

CREATE MATERIALIZED VIEW LOG ON bxj_objects_t1;

CREATE MATERIALIZED VIEW LOG ON bxj_objects_t2;
   
CREATE MATERIALIZED VIEW LOG ON bxj_objects_t3;

 

select * from DBA_MVIEW_lOGS 

select * from MLOG$_BXJ_OBJECTS_T1

select * from MLOG$_BXJ_OBJECTS_T2

select * from MLOG$_BXJ_OBJECTS_T3

 

Step3. 创建物化视图

CREATE MATERIALIZED VIEW bxj_objects_mv_t1 REFRESH FAST AS SELECT * FROM apps.bxj_objects_t1;

CREATE MATERIALIZED VIEW bxj_objects_mv_t2 REFRESH FORCE AS SELECT * FROM bxj_objects_t2;

CREATE MATERIALIZED VIEW bxj_objects_mv_t3 REFRESH COMPLETE AS SELECT * FROM bxj_objects_t3;

 

Step4. 创建物化视图Refresh Group

EXEC DBMS_REFRESH.MAKE('REP_MVIEWGROUP', 'BXJ_OBJECTS_MV_T1,BXJ_OBJECTS_MV_T2,BXJ_OBJECTS_MV_T3', SYSDATE, 'SYSDATE + 1')

 

Step5. 刷新物化视图

EXEC DBMS_MVIEW.refresh('BXJ_OBJECTS_MV_T1','C');

EXEC DBMS_REFRESH.refresh('REP_MVIEWGROUP');

 

 Step6. 加入dbms_jobs，定时刷新物化视图

DECLARE
   jobno   NUMBER;                                             --通过查看该变量可以得到返回的作业编号
BEGIN
   DBMS_JOB.SUBMIT (
      jobno,
      'DBMS_REFRESH.refresh(''' || 'REP_MVIEWGROUP' || ''');', --执行脚本程序
      SYSDATE,                                                 --现在执行
      'SYSDATE+1'
   );
END;

 

Thanks and Regards