drex drex's questions

我从这个过程中得到缓慢的表现

CREATE PROCEDURE MyProcedure01
  @date datetime2(7)
  AS
BEGIN
SELECT 
[Limit1].[C2] AS [C1], 
[Limit1].[mc_object] AS [mc_object], 
[Limit1].[C1] AS [C2]
FROM ( SELECT TOP (50) 
    [GroupBy1].[A1] AS [C1], 
    [GroupBy1].[K1] AS [mc_object], 
    1 AS [C2]
    FROM ( SELECT 
        [Extent1].[mc_object] AS [K1], 
        COUNT(1) AS [A1]
        FROM [dbo].[BEM_EVT_FULL] AS [Extent1]
        WHERE [Extent1].[date_reception] > @date
        GROUP BY [Extent1].[mc_object]
    )  AS [GroupBy1]
)  AS [Limit1]
END

在做了一些搜索之后，我发现如果以这种方式声明变量，我们将解决参数嗅探问题。

CREATE PROCEDURE MyProcedure02
  @date datetime2(7)
  AS
BEGIN
DECLARE @myDate datetime2(7)
 SET @myDate = @date
 SELECT 
[Limit1].[C2] AS [C1], 
[Limit1].[mc_object] AS [mc_object], 
[Limit1].[C1] AS [C2]
FROM ( SELECT TOP (50) 
    [GroupBy1].[A1] AS [C1], 
    [GroupBy1].[K1] AS [mc_object], 
    1 AS [C2]
    FROM ( SELECT 
        [Extent1].[mc_object] AS [K1], 
        COUNT(1) AS [A1]
        FROM [dbo].[BEM_EVT_FULL] AS [Extent1]
        WHERE [Extent1].[date_reception] > @myDate
        GROUP BY [Extent1].[mc_object]
    )  AS [GroupBy1]
)  AS [Limit1]
END

但不幸的是结果仍然很慢我能知道我是否遗漏了什么吗