SQL 服务器 - DATEDIFF 函数耗时太长

Question

我做了一些广泛的研究，得出的结论是 DATEDIFF 函数使我的查询运行非常慢。

下面是 Entity Framework 生成的查询，希望它看起来确实足够可读。

这是生成 T-SQL 的 Linq:

model.NewTotal1Week = ( from sdo in context.SubscriberDebitOrders
                        where
                        (
                           sdo.CampaignId == campaignId &&
                           ( sdo.Status == ( Int32 ) DebitOrderStatus.New_Faulty ) &&
                           ( SqlFunctions.DateDiff( "week", sdo.Collections.FirstOrDefault( c => c.TxnStatus == "U" ).ProcessDate, DateTime.Now ) <= 1 )
                        )
                        select sdo ).Count();

在下面的查询中，我想获取从处理时间到今天的 1 周内的所有集合的 COUNT 个。

有没有人可以帮我去掉 DATEDIFF 函数？我在网上看过例子，但我不能适应我的场景，原谅我还不是很天才。

exec sp_executesql N'SELECT 
    [GroupBy1].[A1] AS [C1]
    FROM ( SELECT 
        COUNT(1) AS [A1]
        FROM  [dbo].[SubscriberDebitOrder] AS [Extent1]
        OUTER APPLY  (SELECT TOP (1) 
            [Extent2].[ProcessDate] AS [ProcessDate]
            FROM [dbo].[Collections] AS [Extent2]
            WHERE ([Extent1].[Id] = [Extent2].[DebitOrderId]) AND (''U'' = [Extent2].[TxnStatus]) ) AS [Limit1]
        WHERE ([Extent1].[CampaignId] = @p__linq__0) AND (3 = [Extent1].[Status]) AND ((DATEDIFF(week, [Limit1].[ProcessDate], SysDateTime())) <= 1)
    )  AS [GroupBy1]',N'@p__linq__0 int',@p__linq__0=3
go

提前致谢。

Answer 1

它不仅仅是 DATEDIFF，列上的任何函数都会导致查询对基础 table/index

进行扫描

DATEDIFF(week, [Limit1].[ProcessDate], SysDateTime())) <=1

以上逻辑是取上周数据？您也可以在不将函数放在 ProcessDate 列周围的情况下编写上面的代码。

[Limit1].[ProcessDate] > SysDateTime()-7

Answer 2

这是您的查询：

SELECT GroupBy1.A1 AS C1
FROM (SELECT COUNT(1) AS[A1
      FROM dbo.SubscriberDebitOrder AS Extent1 OUTER APPLY
           (SELECT TOP (1) Extent2.ProcessDate 
            FROM [dbo].Collections Extent2
            WHERE (Extent1.Id = Extent2.DebitOrderId AND
                   'U' = Extent2.TxnStatus
           ) AS [Limit1]
      WHERE (Extent1.CampaignId = @p__linq__0) AND (3 = Extent1.Status) AND 
            (DATEDIFF(week, Limit1.ProcessDate, SysDateTime()) <= 1)
     )  GroupBy1;

如其他地方所述，您应该更改日期逻辑并摆脱外部查询：

      SELECT COUNT(1) AS A1
      FROM dbo.SubscriberDebitOrder AS Extent1 OUTER APPLY
           (SELECT TOP (1) Extent2.ProcessDate 
            FROM [dbo].Collections Extent2
            WHERE (Extent1.Id = Extent2.DebitOrderId AND
                   'U' = Extent2.TxnStatus
           ) AS limit1
      WHERE (Extent1.CampaignId = @p__linq__0) AND (3 = Extent1.Status) AND 
            Limit1.ProcessDate <= DATEADD(-1, week, GETDATE())

非常重要的说明：这与您的查询不完全相同。您的原始查询计算了两个日期之间的周界数。这取决于 datefirst，但通常是周六或周日晚上的数量。

根据您的描述，上面的比较正确。

接下来，您需要在 Collections(DebitOrderId, TxnStatus, ProcessDate) 和 SubscriberDebitOrder(CampaignId, Status) 上建立索引。

SQL 服务器 - DATEDIFF 函数耗时太长

SQL Server - DATEDIFF Function taking too long

c#

sql

sql-server

entity-framework

linq-to-sql