Question

I am currently using Entity Framework 4.2 with Code First. I currently have a Windows 2008 application server and a database server running on Amazon EC2. The application server has a Windows Service installed that runs once per day. The service executes the following code:

// returns between 2000-4000 records
var users = userRepository.GetSomeUsers();

// do some work

foreach (var user in users)
{
    var userProcessed = new UserProcessed { User = user };
    userProcessedRepository.Add(userProcessed);
}

// Calls SaveChanges() on DbContext
unitOfWork.Commit();

This code takes a few minutes to run. It also maxes out the CPU on the application server. I have tried the following measures:

• Remove the unitOfWork.Commit() to see if it is network related when the application server talks to the database. This did not change the outcome.
• Changed my application server from a medium instance to a high CPU instance on Amazon to see if it is resource related. This caused the server not to max out the CPU anymore and the execution time improved slightly. However, the execution time was still a few minutes.

As a test I modified the above code to run three times to see if execution time for the second and third loop using the same DbContext. Every consecutive loop took longer to run that the previous one but that could be related to using the same DbContext.

Am I missing something? Is it really possible that something as simple as this takes minutes to run? Even if I don’t commit to the database after each loop? Is there a way to speed this up?

Answer 1

Entity Framework (as it stands) isn’t really well suited to this kind of bulk operation. Are you able to use one of the bulk insert methods with EC2? Otherwise, you might find that hand-coding the T-SQL INSERT statements is significantly faster. If performance is important then that probably outweighs the benefits of using EF.