如何强制Linq-To-Sql生成Outer Apply实现关联计数？

我最近在写LINQ查询时遇到了性能瓶颈：想要获取主表TekMas的TekNr列，以及每条主表记录对应的子表TekRev的记录数列表。目前用常规LINQ写法生成的SQL用了嵌套子查询，耗时高达15秒；但我手动编写的带OUTER APPLY的SQL，执行时间不到1秒，性能差异非常明显。

当前LINQ代码及生成的SQL #

LINQ代码 #

TekMas.Select(x => new {x.TekNr,Cnt = x.TekRev.Count})

生成的SQL #

SELECT [Extent1].[TekMasID] AS [TekMasID], [Extent1].[TekNr] AS [TekNr], (SELECT COUNT(1) AS [A1] FROM [dbo].[TekRev] AS [Extent2] WHERE [Extent1].[TekMasID] = [Extent2].[TekMasID]) AS [C1] FROM [dbo].[TekMas] AS [Extent1]

期望生成的SQL #

SELECT TekMas.TekNr, RevCnt.Cnt FROM TekMas OUTER APPLY ( SELECT COUNT (TekRevID) AS Cnt FROM TekRev WHERE TekRev.TekMasID = TekMas.TekMasID) RevCnt;

已知的FirstOrDefault生成OUTER APPLY示例 #

我了解到使用FirstOrDefault的时候，LINQ会生成OUTER APPLY语句，比如下面的代码：

LINQ代码 #

TekMas.Select(x => new { x.TekNr, Cnt = x.TekRev.FirstOrDefault() })
.Select(x => new { x.TekNr, x.Cnt.TekRevID, x.Cnt.TekRevInf })

生成的SQL #

SELECT [Extent1].[TekMasID] AS [TekMasID], [Extent1].[TekNr] AS [TekNr], [Limit1].[TekRevID] AS [TekRevID], [Limit1].[TekRevInf] AS [TekRevInf] FROM [dbo].[TekMas] AS [Extent1] OUTER APPLY (SELECT TOP (1) [Extent2].[TekRevID] AS [TekRevID], [Extent2].[TekRevInf] AS [TekRevInf] FROM [dbo].[TekRev] AS [Extent2] WHERE [Extent1].[TekMasID] = [Extent2].[TekMasID] ) AS [Limit1]

现在我想请教的是：在使用Count统计子表记录数时，怎么让LINQ像FirstOrDefault一样生成OUTER APPLY语句，而不是嵌套子查询呢？

内容的提问来源于stack exchange，提问作者Zer0ne