实体框架执行了太多查询

Question

我需要找到特定用户的不同活动。用户拥有代码权限，代码权限包含代码，代码包含活动。下面是CodeRight类

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; }
}

我将为此编写以下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)

用EF写下面的代码:

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

现在在分析中，我看到EF正在为每个CodeRight执行2个SQL查询。

我还计算了整个执行的时间，EF在使用ADO时需要~400 ms。净值只有~8。

现在我的问题是，如果EF真的这么慢，或者我做错了什么?

编辑

为每个CodeRight

执行以下两个块

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

您应该花时间查看实体框架的Fetch计划。为了让EF执行连接，您必须使用Include关键字。

当你得到你的user对象时，它必须是你初始查询的一部分:

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