EntityFramework生成此查询：
SELECT
[Project1].[Ocr_Status] AS [Ocr_Status],
[Project1].[Id] AS [Id],
[Project1].[Caption] AS [Caption],
[Project1].[Name] AS [Name],
[Project1].[Description] AS [Description],
[Project1].[Url] AS [Url],
[Project1].[PictureUri] AS [PictureUri],
[Project1].[ThumbnailUri] AS [ThumbnailUri],
[Project1].[ValidFrom] AS [ValidFrom],
[Project1].[ValidTo] AS [ValidTo],
[Project1].[VisibleFrom] AS [VisibleFrom],
[Project1].[VisibleTo] AS [VisibleTo],
[Project1].[Ocr_Id] AS [Ocr_Id],
[Project1].[Status] AS [Status],
[Project1].[Gradient_Width] AS [Gradient_Width],
[Project1].[Gradient_Color] AS [Gradient_Color],
[Project1].[BrandId] AS [BrandId],
[Project1].[StoreOfflineJson] AS [StoreOfflineJson],
[Project1].[CreatedBy] AS [CreatedBy],
[Project1].[CreatedOn] AS [CreatedOn],
[Project1].[LastModifiedBy] AS [LastModifiedBy],
[Project1].[LastModifiedOn] AS [LastModifiedOn],
[Project1].[RowVersion] AS [RowVersion],
[Project1].[C1] AS [C1],
[Project1].[Id1] AS [Id1],
[Project1].[PictureUri1] AS [PictureUri1],
[Project1].[Page] AS [Page],
[Project1].[Text] AS [Text],
[Project1].[FlyerId] AS [FlyerId],
[Project1].[CreatedBy1] AS [CreatedBy1],
[Project1].[CreatedOn1] AS [CreatedOn1],
[Project1].[LastModifiedBy1] AS [LastModifiedBy1],
[Project1].[LastModifiedOn1] AS [LastModifiedOn1],
[Project1].[RowVersion1] AS [RowVersion1]
FROM ( SELECT
[Extent1].[Id] AS [Id],
[Extent1].[Caption] AS [Caption],
[Extent1].[Name] AS [Name],
[Extent1].[Description] AS [Description],
[Extent1].[Url] AS [Url],
[Extent1].[PictureUri] AS [PictureUri],
[Extent1].[ThumbnailUri] AS [ThumbnailUri],
[Extent1].[ValidFrom] AS [ValidFrom],
[Extent1].[ValidTo] AS [ValidTo],
[Extent1].[VisibleFrom] AS [VisibleFrom],
[Extent1].[VisibleTo] AS [VisibleTo],
[Extent1].[Ocr_Id] AS [Ocr_Id],
[Extent1].[Ocr_Status] AS [Ocr_Status],
[Extent1].[Status] AS [Status],
[Extent1].[Gradient_Width] AS [Gradient_Width],
[Extent1].[Gradient_Color] AS [Gradient_Color],
[Extent1].[BrandId] AS [BrandId],
[Extent1].[StoreOfflineJson] AS [StoreOfflineJson],
[Extent1].[CreatedBy] AS [CreatedBy],
[Extent1].[CreatedOn] AS [CreatedOn],
[Extent1].[LastModifiedBy] AS [LastModifiedBy],
[Extent1].[LastModifiedOn] AS [LastModifiedOn],
[Extent1].[RowVersion] AS [RowVersion],
[Extent2].[Id] AS [Id1],
[Extent2].[PictureUri] AS [PictureUri1],
[Extent2].[Page] AS [Page],
[Extent2].[Text] AS [Text],
[Extent2].[FlyerId] AS [FlyerId],
[Extent2].[CreatedBy] AS [CreatedBy1],
[Extent2].[CreatedOn] AS [CreatedOn1],
[Extent2].[LastModifiedBy] AS [LastModifiedBy1],
[Extent2].[LastModifiedOn] AS [LastModifiedOn1],
[Extent2].[RowVersion] AS [RowVersion1],
CASE WHEN ([Extent2].[Id] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1]
FROM [Flyers].[Flyers] AS [Extent1]
LEFT OUTER JOIN [Flyers].[Pages] AS [Extent2] ON [Extent1].[Id] = [Extent2].[FlyerId]
WHERE ( NOT (((( CAST( [Extent1].[Status] AS int)) & ( CAST( 4 AS int))) = 4) AND ((CASE WHEN (( CAST( [Extent1].[Status] AS int)) & ( CAST( 4 AS int)) IS NULL) THEN cast(1 as bit) ELSE cast(0 as bit) END) = 0))) AND ( NOT (((( CAST( [Extent1].[Status] AS int)) & ( CAST( 1 AS int))) = 1) AND ((CASE WHEN (( CAST( [Extent1].[Status] AS int)) & ( CAST( 1 AS int)) IS NULL) THEN cast(1 as bit) ELSE cast(0 as bit) END) = 0))) AND ((( CAST( [Extent1].[Status] AS int)) & ( CAST( 2 AS int))) = 2) AND (3 = [Extent1].[Ocr_Status])
) AS [Project1]
ORDER BY [Project1].[Id] ASC, [Project1].[C1] ASC
在MSSMS中，此查询在 1-3s 中完成，但在app中：
-- Executing asynchronously at 30.05.2017 11:19:40 +02:00
-- Completed in **525 ms** with result: SqlDataReader
所以查询在 0.5s 中完成了吗？
然后是投影时间。需要 6-10分钟。
return await Context.Flyers.Where(predicate).Include(f => f.Pages).ToListAsync();
发生了什么事？大约有300行。
谓词看起来像这样：
Expression<Func<BackOfficeFlyer, bool>> exsp = flyer =>
!flyer.Status.HasFlag(FlyerStatus.Active) &&
!flyer.Status.HasFlag(FlyerStatus.Deleted) &&
flyer.Status.HasFlag(FlyerStatus.Validated) &&
flyer.Ocr.Status == OcrStatus.Finished;