在SQL Server中索引视图跟物化视图(materialized View)有点类似。索引视图的最大好处是可以物化一个大表的摘要合计 (materialize summary aggregates of a large table),例如,考虑到一个customer表包含几百万行美国的顾客,而你想要统计每个州的相关信息。你可以创建一个基于Group by查询的视图
Besides the standard role of basic user-defined views, SQL Server provides the following types of views that serve special purposes in a database. Indexed views An indexed view is a materialized view. This means the view definition has been computed and the resulting data stored just like a ...
适用范围:SQL Server 现象 对链接服务器上的视图执行查询所需的时间比直接对链接服务器上的基表执行同一查询所需的时间要长。 原因 对视图执行查询和基表会导致不同的行为,因为数据基数估计用于计算返回的预期行数。 查询视图的数字设置为常量值 10,000,而查询基表的数字派生自统计信息。
Consider a switch from a commercial to an open source database. Explore the key differences and similarities between PostgreSQL and SQL Server
All DB-Library values must be set correctly either at the server level by using sp_configure or from the application by using the SET command. Important We strongly recommend that you set the ARITHABORT user option to ON server-wide as soon as the first indexed view or index on a computed...
If I run this locally on SQL Server running through Docker (2022:latest), I get the following error Msg 8668, Level 16, State 0, Line 34 Cannot create the clustered index 'IDX_Index' on view 'services-import.schema.IndexedView' because the select list of the view contains...
在1.4 系列中引入的戏剧性性能改进,并在 ORM Batch inserts with psycopg2 now batch statements with RETURNING in most cases 中描述,现已推广到所有支持 RETURNING 的包含后端,除了 MySQL 之外的所有后端:SQLite,MariaDB,PostgreSQL(所有驱动程序)和 Oracle; SQL Server 具有支持,但在版本 2.0.9 中暂时禁用[1]...
虽然原始功能对于 psycopg2 驱动程序最为关键,否则在使用cursor.executemany()时会有严重的性能问题,但该变更对于其他 PostgreSQL 驱动程序如 asyncpg 同样关键,因为在使用 RETURNING 时,单语句 INSERT 语句仍然不可接受地慢,以及在使用 SQL Server 时,似乎无论是否使用 RETURNING,INSERT 语句的 executemany 速度都非常慢...
Use the "Checklist: SQL Server Performance" checklist to quickly view and evaluate the guidelines presented in this chapter.SQL: Scale Up vs. Scale OutScaling up refers to moving an application to a larger class of hardware that uses more powerful processors, more memory, and quicker disk ...
In the Developer and Enterprise editions of SQL Server 2000 and SQL Server 2005, the query processor can use an indexed view to solve queries that structurally match the view, even if they don't refer to the view by name. In other versions, you must reference the view by name and use ...