Question

Does lazy loading load the entire collection even if you only iterate over the first item in the collection? Or does it only load the items that are iterated over within the collection?

…or do I have no idea what I’m talking about?

Answer 1

Lazy loading loads the whole collection when you start to iterate over the collection. Example: Suppose user 1 has the role “Role1”, “Role2”, “Role3” (user.Roles is virtual):

var user = context.Users.Single(u => u.Id == 1);
foreach (var role in user.Roles) // DB query happens here once
{
    Console.WriteLine(role.Name);
    if (role.Name == "Role1")
        break;
}

Although you never access Role2 and Role3 they have been loaded nonetheless.