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POEntity Framework include Extension Returns a Ton of Data
 

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    <p>I have two entities, User and UserPermission. The User entity contains all your normal fields, Id, Username, Email, etc and the UserPermission entity has two values, UserId and PermissionId. I have written a repository method GetUserWithPermissions that originally utilized the Include extension and did something like this:</p> <pre><code>return dbContext.Users.Include(u =&gt; u.UserPermission).Where(u =&gt; u.Username.Equals(username)).FirstOrDefault(); </code></pre> <p>It works great but the issues is that there are going to be a bunch of UserPermission entities associated with any given user and using the Include extension essentially just flattens the two tables into one so ALL of the user fields are repeated for every single UserPermission associated with a User. The returned data looks something like this:</p> <pre><code>Id Username Email ... PermissionId 1 johndoe john@email.com 1 1 johndoe john@email.com 2 1 johndoe john@email.com 3 1 johndoe john@email.com 4 1 johndoe john@email.com 5 1 johndoe john@email.com 6 1 johndoe john@email.com 7 </code></pre> <p>The only difference between each row is the last column PermissionId. If we have 50 permissions defined for the user, that is a large chunk of repeated data being returned when I do not think it is necessary. Obviously my other option is to do something like this:</p> <pre><code>User user = dbContext.Users.Where(u =&gt; u.Username.Equals(username)).FirstOrDefault(); if (user != null) user.UserPermissions.ToList(); return user; </code></pre> <p>The above code accomplishes the same thing with drastically less data being returned but with the trade off that two trips are being made to the database.</p> <p>Which method is better? Returning a lot of repeated data or making two trips to the database?</p> <p>Here is the SQL query that is generated by the Entity Framework</p> <pre><code>SELECT [Project2].[Id] AS [Id], [Project2].[Username] AS [Username], [Project2].[LoweredUsername] AS [LoweredUsername], [Project2].[CompanyId] AS [CompanyId], [Project2].[FirstName] AS [FirstName], [Project2].[LastName] AS [LastName], [Project2].[Email] AS [Email], [Project2].[C1] AS [C1], [Project2].[UserId] AS [UserId], [Project2].[PermissionValue] AS [PermissionValue] FROM ( SELECT [Limit1].[Id] AS [Id], [Limit1].[Username] AS [Username], [Limit1].[LoweredUsername] AS [LoweredUsername], [Limit1].[CompanyId] AS [CompanyId], [Limit1].[FirstName] AS [FirstName], [Limit1].[LastName] AS [LastName], [Limit1].[Email] AS [Email], [Extent2].[UserId] AS [UserId], [Extent2].[PermissionValue] AS [PermissionValue], CASE WHEN ([Extent2].[PermissionValue] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1] FROM (SELECT TOP (1) [Extent1].[Id] AS [Id], [Extent1].[Username] AS [Username], [Extent1].[LoweredUsername] AS [LoweredUsername], [Extent1].[CompanyId] AS [CompanyId], [Extent1].[FirstName] AS [FirstName], [Extent1].[LastName] AS [LastName], [Extent1].[Email] AS [Email] FROM [dbo].[Users] AS [Extent1] WHERE [Extent1].[LoweredUsername] = (LOWER(LTRIM(RTRIM(@p__linq__0)))) ) AS [Limit1] LEFT OUTER JOIN [dbo].[UserPermissions] AS [Extent2] ON [Limit1].[Id] = [Extent2].[UserId] ) AS [Project2] ORDER BY [Project2].[Id] ASC, [Project2].[C1] ASC </code></pre> <p>Thanks</p> <p>Nick</p>
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    1. COLooks like I misunderstood your question - I take it this is about optimization, the results for both of your approaches are the same.
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    2. CO@BrokenGlass So you are saying returning a bunch of duplicated data in one database call is the same as returning significantly less data with two database calls?
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    3. CONo - the resulting `User` entities are the same, performance might differ.
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