實體框架正在執行太多查詢

Question

我需要找到特定用戶的不同廣告系列。 用戶擁有CodeRights，CodeRights包含包含Campaign的代碼和代碼。 這是CodeRight類

public class SmartCodeRight
{
        [Key, Column(Order = 1)]
        public long UserId { get; set; }
        public virtual User User { get; set; }

        [Key, Column(Order = 2)]
        public long CodeId { get; set; }
        public virtual SmartCode Code { get; set; }

        public CodeRight CodeRight { get; set; }
}

我會為此編寫以下SQL：

SELECT * 
FROM campaigns 
WHERE campaignid IN (SELECT DISTINCT campaignid  
                     FROM smartcodes t1 
                     INNER JOIN smartcoderights t2 ON t1.codeId = t2.codeId
                     WHERE t2.userid = @userId)

使用EF我正在寫這段代碼：

var v = user.CodeRights.Select(r => r.Code.Campaign).Distinct().ToList();

現在，在分析時，我發現EF正在為每個存在的CodeRight執行2個SQL查詢。

我還計算了整個執行的時間， EF使用ADO.Net需要大約400毫秒，它只有〜8 。

現在我的問題是，如果EF真的很慢或者我做錯了什么？

編輯

正在為每個CodeRight執行以下兩個塊

exec sp_executesql N'SELECT 
[Extent1].[CodeId] AS [CodeId], 
[Extent1].[CodeTitle] AS [CodeTitle], 
[Extent1].[CodeContent] AS [CodeContent], 
[Extent1].[CreatedOn] AS [CreatedOn], 
[Extent1].[IsActive] AS [IsActive], 
[Extent1].[Deleted] AS [Deleted], 
[Extent1].[OwnerId] AS [OwnerId], 
[Extent1].[Tags] AS [Tags], 
[Extent1].[CampaignId] AS [CampaignId]
FROM [dbo].[SmartCodes] AS [Extent1]
WHERE [Extent1].[CodeId] = @EntityKeyValue1',N'@EntityKeyValue1 bigint',@EntityKeyValue1=24
go

和

exec sp_executesql N'SELECT 
[Extent1].[CampaignId] AS [CampaignId], 
[Extent1].[Name] AS [Name], 
[Extent1].[Description] AS [Description], 
[Extent1].[AdminId] AS [AdminId]
FROM [dbo].[Campaigns] AS [Extent1]
WHERE [Extent1].[CampaignId] = @EntityKeyValue1',N'@EntityKeyValue1 int',@EntityKeyValue1=12
go

Answer 1

您應該花時間查看實體框架的獲取計划 。 要使EF執行連接，您必須使用Include關鍵字。

當您獲得user對象時，它必須是初始查詢的一部分：

var user = context.Users
    .Include("CodeRights.Code")
    .Include("CodeRights.Campaign")
    .FirstOrD‌​efault(u => u.Id == id);