How can I make the Entity Framework generated SQL cleaner

Question

I am using the Entity Framework with SQL Server Express 2008. When using the profiler, I see SQL being generated like this:

SELECT 
[Project1].[C1] AS [C1], 
[Project1].[EmployeeID] AS [EmployeeID], 
[Project1].[FirstName] AS [FirstName], 
[Project1].[LastName] AS [LastName], 
[Project1].[Active] AS [Active], 
[Project1].[Updated] AS [Updated], 
[Project1].[Created] AS [Created], 
[Project1].[CreatedBy] AS [CreatedBy], 
[Project1].[Modified] AS [Modified], 
[Project1].[ModifiedBy] AS [ModifiedBy]
FROM ( SELECT 
    [Extent1].[EmployeeID] AS [EmployeeID], 
    [Extent1].[FirstName] AS [FirstName], 
    [Extent1].[LastName] AS [LastName], 
    [Extent1].[Active] AS [Active], 
    [Extent1].[Updated] AS [Updated], 
    [Extent1].[Created] AS [Created], 
    [Extent1].[CreatedBy] AS [CreatedBy], 
    [Extent1].[Modified] AS [Modified], 
    [Extent1].[ModifiedBy] AS [ModifiedBy], 
    1 AS [C1]
    FROM [dbo].[Employee] AS [Extent1]
)  AS [Project1]
ORDER BY [Project1].[LastName] ASC

Does having what I call a sub query effect the performance of SQL Server and or my application? If I were to write this SQL query by hand, it would look more like this:

SELECT 
[Project1].[EmployeeID] AS [EmployeeID], 
[Project1].[FirstName] AS [FirstName], 
[Project1].[LastName] AS [LastName], 
[Project1].[Active] AS [Active], 
[Project1].[Updated] AS [Updated], 
[Project1].[Created] AS [Created], 
[Project1].[CreatedBy] AS [CreatedBy], 
[Project1].[Modified] AS [Modified], 
[Project1].[ModifiedBy] AS [ModifiedBy]
FROM [dbo].[Employee] AS [Project1]
ORDER BY [Project1].[LastName] ASC

Is there a way to make this cleaner? Why is the sub query created? Should I care? I am using LinqToEntities. Here is the function that created the first SQL sample:

public DTO.EmployeeDTO[] GetEmployees()
{
    using (KDMEntities ctx = new KDMEntities())
    {
        var employees = (from e in ctx.Employees
                         orderby e.LastName
                         select new DTO.EmployeeDTO
                         {
                             EmployeeID = e.EmployeeID,
                             FirstName = e.FirstName,
                             LastName = e.LastName,
                             Active = e.Active,
                             Updated = e.Updated,
                             Created = e.Created,
                             CreatedBy = e.CreatedBy,
                             Modified = e.Modified,
                             ModifiedBy = e.ModifiedBy
                         }).ToArray();
        return employees;
    }
}

Answer 1

First of all, I'd say as long as you do get "good enough" performance, it's the classic trade-off between productivity (you don't have to deal with constructing each and every bit of SQL and manually reading SqlDataReaders etc. anymore) and potentially performance.

Measure, measure, measure - and see if it's really a problem before prematurely over-optimizing. Don't do it.

Second, I don't know of any extension points that are available for you to hook into the SQL generation process in EF - so basically you're left with the choice of: is the performance good enough and can I get used to the fact that EF might generate certain statement differently than I would manually - or then drop it and use something else.

Again: it's a trade-off, as almost everything in IT - usually it's performance vs. productivity, and as long as the performance is "good enough", I wouldn't spend a minute on optimizing - your users and managers and customers don't really care.