带日期部分的索引视图，日期部分上的查询未使用索引

Question

我需要在 datepart(day, BornDate) and/or 个月之前在一个有几百万行的 table 上进行查询，这非常 CPU 密集。

我尝试将索引视图与日期部分列一起使用，甚至在索引视图本身的 datepart(day, BornDate) 列上创建非聚集索引。但是执行计划仍然告诉我查询是在基础 table.

上使用 datepart 计算的

我运行的查询如下：

set statistics time on
SELECT count(1) FROM [dbo].[DemandsBornDateParts] where borndateday = 5 OPTION (RECOMPILE)
set statistics time off

我总是将它与针对基础 table:

的相同查询进行比较

set statistics time on
select count(1) from dbo.Demands where DAY(borndate) = 5
set statistics time off

它们都显示几乎相同的查询计划，具有几乎相同的子树成本、CPU 和运行时间，都使用谓词 datepart(day,[dbo].[Demands].[BornDate])=(5)

进行聚簇索引扫描

视图定义如下：

GO  
--Set the options to support indexed views.  
SET NUMERIC_ROUNDABORT OFF;  
SET ANSI_PADDING, ANSI_WARNINGS, CONCAT_NULL_YIELDS_NULL, ARITHABORT,  
    QUOTED_IDENTIFIER, ANSI_NULLS ON;  
GO  
--Create view with schemabinding.  
IF OBJECT_ID ('dbo.DemandsBornDateParts', 'view') IS NOT NULL  
DROP VIEW dbo.DemandsBornDateParts ;  
GO  
CREATE VIEW dbo.DemandsBornDateParts
WITH SCHEMABINDING  
AS  
    SELECT id,
           Datepart(DAY, borndate)   AS BornDateDay,
           Datepart(MONTH, borndate) AS BornDateMonth,
           Datepart(YEAR, borndate)  AS BornDateYear
    FROM   DBO.demands  
GO  

--Create an index on the view.  
CREATE UNIQUE CLUSTERED INDEX [PK_dbo.DemandsBornDateParts]
    ON dbo.DemandsBornDateParts (Id);  
GO
CREATE NONCLUSTERED INDEX [IX_BornDateDay] ON [dbo].[DemandsBornDateParts]
(
    [BornDateDay] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO

如何才能使用 persisted/indexed 列，而无需一遍又一遍地重新计算 datepart？我不能使用持久化列，我需要使用视图。

Answer 1

在查询中的视图名称后添加 WITH(NOEXPAND)。来自 Table Hints 的文档：

NOEXPAND

Specifies that any indexed views are not expanded to access underlying tables when the query optimizer processes the query. The query optimizer treats the view like a table with clustered index. NOEXPAND applies only to indexed views.

来自同一页上的Remarks on Using NOEXPAND：

To force the optimizer to use an index for an indexed view, specify the NOEXPAND option.

带日期部分的索引视图，日期部分上的查询未使用索引

Indexed view with datepart, query on datepart is not using the index

sql-server

sql-server-2008

tsql

indexed-view