Entity Framework 6.1.3 exec sp_executesql大きなパフォーマンスの問題が発生しました

Question

SQL Serverデータベースに対して非常に遅い（2レコードで30秒）非常に基本的なEntity Frameworkクエリがあります。私は、データベース上で実行取得実際のクエリを得るために私達のDBAと協力：

exec sp_executesql N'SELECT 
    [Project1].[DocumentID] AS [DocumentID], 
    [Project1].[CreationDate] AS [CreationDate], 
    [Project1].[DocType] AS [DocType] 
    FROM (SELECT 
     [Extent1].[DocumentID] AS [DocumentID], 
     [Extent1].[DocType] AS [DocType], 
     [Extent1].[CreationDate] AS [CreationDate] 
     FROM [dbo].[DocFile] AS [Extent1] 
     LEFT OUTER JOIN [dbo].[Demographics] AS [Extent2] ON [Extent1].[DemographicsKey] = [Extent2].[DemographicsKey] 
     LEFT OUTER JOIN [dbo].[Client] AS [Extent3] ON [Extent1].[ClientKey] = [Extent3].[ClientKey] 
     WHERE (([Extent1].[DocType] = @p__linq__0) OR (([Extent1].[DocType] IS NULL) AND (@p__linq__0 IS NULL))) AND ([Extent1].[CreationDate] >= @p__linq__1) AND (([Extent2].[SSN] = @p__linq__2) OR (([Extent2].[SSN] IS NULL) AND (@p__linq__2 IS NULL))) AND (([Extent3].[ControlNumber] = @p__linq__3) OR (([Extent3].[ControlNumber] IS NULL) AND (@p__linq__3 IS NULL))) 
    ) AS [Project1] 
    ORDER BY [Project1].[CreationDate] DESC',N'@p__linq__0 nvarchar(4000),@p__linq__1 datetime2(7),@p__linq__2 nvarchar(4000),@p__linq__3 nvarchar(4000)',@p__linq__0=N'AST',@p__linq__1='2013-07-01 15:52:25.4288579',@p__linq__2=N'818760001',@p__linq__3=N'8187600002' 

私はSQL Server Management Studioのからこの正確なクエリを実行すると、それはまた、約30秒かかります。

私は幹部sp_executesqlをを取り出し、インラインで変数を交換するときただし、クエリはわずか数ミリ秒かかる値：これら2つのクエリは、このような劇的に異なるパフォーマンスを持っているでしょうなぜ

SELECT 
    [Project1].[DocumentID] AS [DocumentID], 
    [Project1].[CreationDate] AS [CreationDate], 
    [Project1].[DocType] AS [DocType] 
    FROM (SELECT 
     [Extent1].[DocumentID] AS [DocumentID], 
     [Extent1].[DocType] AS [DocType], 
     [Extent1].[CreationDate] AS [CreationDate] 
     FROM [dbo].[DocFile] AS [Extent1] 
     LEFT OUTER JOIN [dbo].[Demographics] AS [Extent2] ON [Extent1].[DemographicsKey] = [Extent2].[DemographicsKey] 
     LEFT OUTER JOIN [dbo].[Client] AS [Extent3] ON [Extent1].[ClientKey] = [Extent3].[ClientKey] 
     WHERE (([Extent1].[DocType] = 'AST') OR (([Extent1].[DocType] IS NULL) AND ('AST' IS NULL))) AND ([Extent1].[CreationDate] >= '7/1/2013') AND (([Extent2].[SSN] = '818760002') OR (([Extent2].[SSN] IS NULL) AND ('818760002' IS NULL))) AND (([Extent3].[ControlNumber] = '8187600002') OR (([Extent3].[ControlNumber] IS NULL) AND ('8187600002' IS NULL))) 
    ) AS [Project1] 

を？ EFコードを修正するか、DBを修正してコードのパフォーマンスを向上させるにはどうすればよいですか？

ありがとうございます！

Answer 1

正しい解決策はここにあるようなので、になります。それはそれがあなたを助けている場合（などはnvarchar対NULL可能タイプまたはvarcharなど）に一致するタイプ

といくつかの問題が喜んでいるでしょうだEntity Framework query slow, but same SQL in SqlQuery is fast

たぶん問題を解く。 ;）