为什么Entity Framework为Azure移动服务表控制器生成以下嵌套SQL
在TableController中使用实体框架时，我试图找出问题的根源
我创建了以下设置。
- 新的Mobile Web API提供了基本的TodoItem示例，该API利用了EntityFramework、TableController和默认的EntityDomainManager
公共类TodoItemController : TableController { protected override void Initialize(HttpControllerContext controllerContext) { base.Initialize(controllerContext)；context =新的MobileServiceContext()；context.Database.Log += LogToDebug；DomainManager =新的EntityDomainManager(context，Request)；}公共IQueryable GetAllTodoItems() { var q= Query()；return q；}
- A vanilla Web API 2控制器。
公共类TodoItemsWebController : ApiController {私有MobileServiceContext db =新MobileServiceContext()；公共TodoItemsWebController() { db.Database.Log += LogToDebug；}公共IQueryable GetTodoItems() { return db.TodoItems；}
我仔细梳理了tablecontroller代码，深入研究了Query方法，该方法只是通过DomainManager代理调用，将Where(_ => !_.IsDeleted)修改添加到IQueryable中
然而，这两个查询产生的SQL却截然不同。
对于常规的Web API Controller，您将获得以下SQL。
SELECT
[Extent1].[Id] AS [Id],
[Extent1].[Version] AS [Version],
[Extent1].[CreatedAt] AS [CreatedAt],
[Extent1].[UpdatedAt] AS [UpdatedAt],
[Extent1].[Deleted] AS [Deleted],
[Extent1].[Text] AS [Text],
[Extent1].[Complete] AS [Complete]
FROM [dbo].[TodoItems] AS [Extent1]但是对于TableController，您会得到以下SQL块，其中中间有一个*魔术* Guid，并产生一个嵌套的SQL语句。当你开始处理像$top，$skip，$filter和$expand这样的ODATAv3查询时，它的性能就变成了垃圾。
SELECT TOP (51)
[Project1].[C1] AS [C1],
[Project1].[C2] AS [C2],
[Project1].[C3] AS [C3],
[Project1].[Complete] AS [Complete],
[Project1].[C4] AS [C4],
[Project1].[Text] AS [Text],
[Project1].[C5] AS [C5],
[Project1].[Deleted] AS [Deleted],
[Project1].[C6] AS [C6],
[Project1].[UpdatedAt] AS [UpdatedAt],
[Project1].[C7] AS [C7],
[Project1].[CreatedAt] AS [CreatedAt],
[Project1].[C8] AS [C8],
[Project1].[Version] AS [Version],
[Project1].[C9] AS [C9],
[Project1].[Id] AS [Id]
FROM ( SELECT
[Extent1].[Id] AS [Id],
[Extent1].[Version] AS [Version],
[Extent1].[CreatedAt] AS [CreatedAt],
[Extent1].[UpdatedAt] AS [UpdatedAt],
[Extent1].[Deleted] AS [Deleted],
[Extent1].[Text] AS [Text],
[Extent1].[Complete] AS [Complete],
1 AS [C1],
N'804f84c6-7576-488a-af10-d7a6402da3bb' AS [C2],
N'Complete' AS [C3],
N'Text' AS [C4],
N'Deleted' AS [C5],
N'UpdatedAt' AS [C6],
N'CreatedAt' AS [C7],
N'Version' AS [C8],
N'Id' AS [C9]
FROM [dbo].[TodoItems] AS [Extent1]
) AS [Project1]
ORDER BY [Project1].[Id] ASC您可以在此处查看这两个查询的结果。https://pastebin.com/tSACq6eg
所以我的问题是：
- 为什么
TableController以这种方式生成SQL？ - 查询中间的*魔术* guid是什么？(它将保持不变，直到我停止并重新启动应用程序，所以我不知道它是会话、客户端还是数据库上下文specific)
- Where，TableController是否正在对
IQueryable进行这些修改？我假设它是通过某个中间件步骤完成的，或者是在调用Query()方法后稍后在请求中的一个on executed属性完成的，但我终生找不到它。
https://stackoverflow.com/questions/45300933
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