1、普通视图 数据库中的视图(view)是从一张或多张数据库表查询导出的虚拟表,反映基础表中数据的变化,且本身不存储数据。 2、物化视图【materialized view】 2.1、概念:物化视图是查询结果集的一份持久化存储,所以它与普通视图完全不同,而非常趋近于表。可以是基础表中部分数据的一份简单拷贝,也可以是多表join之...
1、普通视图 数据库中的视图(view)是从一张或多张数据库表查询导出的虚拟表,反映基础表中数据的变化,且本身不存储数据。 2、物化视图【materialized view】 2.1、概念:物化视图是查询结果集的一份持久化存储,所以它与普通视图完全不同,而非常趋近于表。 可以是基础表中部分数据的一份简单拷贝,也可以是多表join...
描并且在REFRESH MATERIALIZED VIEW被使用前不能被查询。 在该命令被发出时,查询会被执行并且被用来填充该视图(除非使用了 WITH NO DATA),并且后来可能会用 REFRESHMATERIALIZED VIEW进行刷新。 CREATE MATERIALIZED VIEW类似于 CREATE TABLE AS,不过它还会记住被用来初始化该视图的查询, 这样它可以在后来被命令刷新。
Understanding PostgreSQL views and materialized views is key to using the database effectively. Learn the difference between views and materialized views here!
一个有用的物化视图示例是，用于为销售员创建控制面板显示图表。通过计划任务，每天运行特定SQL语句更新该统计信息。创建一个新的物化视图，即通过`CREATE MATERIALIZED VIEW`命令定义，该命令执行查询填充视图，除非使用`WITH NO DATA`选项。之后，可以使用`REFRESH MATERIALIZED VIEW`命令刷新视图内容。物化...
Non-Materialized View - A Non-Materialized view takes the output of a query and makes it appear like a virtual table. You can use a view in most places where a table can be used. All operations performed on a view will affect data in the base table and so are subject to the ...
SQL> CREATE MATERIALIZED VIEW mv_emp_pk REFRESH FAST START WITH SYSDATE NEXT SYSDATE + 2 WITH PRIMARY KEY AS SELECT * FROM emp@remote_db; Materialized view created. In the above example, the first copy of the materialized view is made at SYSDATE and the interval at which the refresh has...
Materialized View responds faster as compared to View. But View always provides up to date information to the user. Related Differences: Difference Between Where and Having Clause in SQL Difference Between Group By and Order By in SQL Difference Between Fact Table and Dimension Table ...
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SQL复制 -- Create a materialized view if it doesn't exist>CREATEMATERIALIZEDVIEWIFNOTEXISTSsubscribed_moviesASSELECTmo.member_id, mb.full_name, mo.movie_titleFROMmoviesASmoINNERJOINmembersASmbONmo.member_id = mb.id;-- Create and schedule a materialized view to be refreshed every day....