SQL Server Profiler 不跟踪所有 Entity Framework 4 查询 - 问题答案

【问题标题】：SQL Server Profiler do not trace all Entity Framework 4 queries - issueSQL Server Profiler 不跟踪所有 Entity Framework 4 查询 - 问题
【发布时间】：2011-12-14 02:53:10
【问题描述】：

我正在阅读Programming Entity Framework, 2nd Edition，在第一章中有一个非常简单的查询：

    private static void QueryContacts()
    {
        using (var context = new SampleEntities())
        {
            var contacts = context.Contacts.Where(c => c.FirstName == "Robert");
            var res = (contacts as ObjectQuery<Contact>).Execute(MergeOption.NoTracking);

            foreach (var contact in res)
            {
                foreach (var address in contact.Addresses)
                {
                    Console.WriteLine("\t{0}", address.City);
                }
            }
        }
        Console.Write("Press Enter...");
        Console.ReadLine();
    }

当我将 SQL 分析器附加到数据库实例时，我可以看到执行了以下 SQL：

SELECT 
[Extent1].[ContactID] AS [ContactID], 
[Extent1].[FirstName] AS [FirstName], 
[Extent1].[LastName] AS [LastName], 
[Extent1].[Title] AS [Title], 
[Extent1].[AddDate] AS [AddDate], 
[Extent1].[ModifiedDate] AS [ModifiedDate]
FROM [dbo].[Contact] AS [Extent1]
WHERE N'Robert' = [Extent1].[FirstName]

但没有查询地址表的迹象（即使有地址）。

当我附加 Entity Framework Profiler 时，我可以看到两者：

SELECT [Extent1].[ContactID]    AS [ContactID],
       [Extent1].[FirstName]    AS [FirstName],
       [Extent1].[LastName]     AS [LastName],
       [Extent1].[Title]        AS [Title],
       [Extent1].[AddDate]      AS [AddDate],
       [Extent1].[ModifiedDate] AS [ModifiedDate]
FROM   [dbo].[Contact] AS [Extent1]
WHERE  N'Robert' = [Extent1].[FirstName]

和

SELECT [Extent1].[addressID]     AS [addressID],
       [Extent1].[Street1]       AS [Street1],
       [Extent1].[Street2]       AS [Street2],
       [Extent1].[City]          AS [City],
       [Extent1].[StateProvince] AS [StateProvince],
       [Extent1].[CountryRegion] AS [CountryRegion],
       [Extent1].[PostalCode]    AS [PostalCode],
       [Extent1].[AddressType]   AS [AddressType],
       [Extent1].[ContactID]     AS [ContactID],
       [Extent1].[ModifiedDate]  AS [ModifiedDate]
FROM   [dbo].[Address] AS [Extent1]
WHERE  [Extent1].[ContactID] = 209 /* @EntityKeyValue1 */

您知道 SQL Server Profiler 发生了什么，因此无法捕获对地址表的查询吗？

谢谢

【问题讨论】：

确保您没有在 SQL 分析器中设置任何过滤器。

标签： .net linq sql-server-2008 entity-framework

【解决方案1】：

宾果游戏！

我选择了所有事件类型，结果发现 Addresses 查询可追踪为 RPC:Completed，而 Contact 可追踪为 SQL:BatchCompleted：

exec sp_executesql N'SELECT 
[Extent1].[addressID] AS [addressID], 
[Extent1].[Street1] AS [Street1], 
[Extent1].[Street2] AS [Street2], 
[Extent1].[City] AS [City], 
[Extent1].[StateProvince] AS [StateProvince], 
[Extent1].[CountryRegion] AS [CountryRegion], 
[Extent1].[PostalCode] AS [PostalCode], 
[Extent1].[AddressType] AS [AddressType], 
[Extent1].[ContactID] AS [ContactID], 
[Extent1].[ModifiedDate] AS [ModifiedDate]
FROM [dbo].[Address] AS [Extent1]
WHERE [Extent1].[ContactID] = @EntityKeyValue1',N'@EntityKeyValue1 int',@EntityKeyValue1=220

【讨论】：

而为什么 [某些] 查询是通过 RPC 和 sp_execsql 执行的？ :>

【解决方案2】：

在你的循环中延迟加载期间会查询地址。使用联系人单次拍摄会更有效。为此，您需要：

var res = (contacts as ObjectQuery<Contact>).Include("Addresses").Execute(MergeOption.NoTracking);

【讨论】：

嗨，我推断地址是延迟加载的，但我没有在 EF4 中控制该功能。这就是我首先启动 SQL Server Profiler 的原因，看看它是如何处理地址的。
所以如果你在调试器中遍历你的循环 Profiler 仍然没有捕捉到任何东西？如果是这样，那么它肯定与过滤器有关。另一个可能的原因 - 具有此 ID 的联系人已在 Context 中具体化，并且其地址也已加载。在这种情况下，您将从 Context 获取您的地址，而无需查询 DB。