SQL Server 2005 表值函数奇怪的性能

Question

1 分钟查询与表值函数中的相同查询之间的执行时间存在巨大差异。

但最奇怪的事情是使用另一个(有效的)company_id 参数运行 UDF 在大约 40 秒内给我一个结果，一旦我将这个 company_id 更改为 12(再次有效)，它就永远不会停止。 这两个查询的执行计划绝对不一样，当然长查询是最复杂的。但是批处理版本和 UDF 版本之间的执行计划是相同的，并且批处理版本速度很快...!

如果我“手动”执行以下查询，则执行时间为 1 分钟 36 秒，包含 306 行:

 SELECT
  dbo.date_only(Call.date) AS date,
  count(DISTINCT customer_id) AS new_customers
 FROM
  Call
 LEFT OUTER JOIN
  dbo.company_new_customers(12, 2009, 2009) new_customers
   ON dbo.date_only(new_customers.date) = dbo.date_only(Call.date)
 WHERE
  company_id = 12
  AND year(Call.date) >= 2009
  AND year(Call.date) <= 2009
 GROUP BY
  dbo.date_only(Call.date)

我将这个完全相同的查询存储在一个函数中并像这样运行它:

SELECT * FROM company_new_customers_count(12, 2009, 2009)

现在它正在运行 13 分钟...我确信它永远不会给我任何结果。

昨天，我在 4 个多小时内出现了完全相同的无限循环行为(所以我停止了它)。

这是函数的定义:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE FUNCTION company_new_customers_count 
( 
 @company_id int, 
 @start_year int,
 @end_year int
)
RETURNS TABLE 
AS
RETURN 
(
 SELECT
  dbo.date_only(Call.date) AS date,
  count(DISTINCT customer_id) AS new_customers
 FROM
  Call
 LEFT OUTER JOIN
  dbo.company_new_customers(@company_id, @start_year, @end_year) new_customers
   ON dbo.date_only(new_customers.date) = dbo.date_only(Call.date)
 WHERE
  company_id = @company_id
  AND year(Call.date) >= @start_year
  AND year(Call.date) <= @end_year
 GROUP BY
  dbo.date_only(Call.date)
)
GO

我很高兴了解正在发生的事情。

谢谢

附加:

company_new_customers 的定义:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Description: Create the list of new customers of @company_id
--          in the given period.
-- =============================================
CREATE FUNCTION company_new_customers 
(   
    @company_id int, 
    @start_year int,
    @end_year   int
)
RETURNS TABLE 
AS
RETURN 
(
    SELECT
        customer_id,
        date
    FROM
    (   -- select apparition dates of cutomers before @end_year
        SELECT
            min(date)       AS date,
            customer_id
        FROM
            Call
        JOIN
            Call_Customer ON Call_Customer.call_id = Call.call_id
        WHERE
            company_id = @company_id
            AND year(date) <= @end_year
        GROUP BY
            customer_id
    ) new_customers
    WHERE
        year(date) >= @start_year -- select apparition dates of cutomers after @start_year
)
GO

date_only 的定义:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:      Julio Guerra
-- Create date: 14/10/2010
-- Description: Return only the date part of a datetime value
-- Example:         date_only('2010-10-25 13:00:12') returns 2010-10-25
-- =============================================
CREATE FUNCTION date_only
(
    @datetime datetime
)
RETURNS datetime
AS
BEGIN
    RETURN dateadd(dd, 0, datediff(dd, 0, @datetime))
END
GO

SELECT * FROM company_new_customers_count(8, 2009, 2009) 的执行计划

SELECT * FROM company_new_customers_count(12, 2009, 2009) 的执行计划

Answer 1

从这些查询计划看来，您可以从这样的索引中受益(如果我正确推断出您的数据库架构):

CREATE INDEX IX_call_company_date ON call (company_id, date)

总的来说，这似乎是一个标准的查询优化问题，表值函数实际上并没有产生什么影响。