Does EF Transaction rollback have an effect on other requests that arrives at the same time?

Question

I am using entity framework 6, in a C# application.

I have the following logic

using (var context = new MyContext())
{
    using (var dbContextTransaction = context.Database.BeginTransaction())
    {
        try
        {
            // Do LogicA
            // Insert a new user to the database 
            context.SaveChanges();

            // Take the inserted userID. 
            // Do LogicB
            context.SaveChanges();

            dbContextTransaction.Commit();
            return user;
        }
        catch (Exception)
        {
            dbContextTransaction.Rollback();
            return null;
        }

    }
}

Basically I am inserting a user to the database in LogicA, and I will need his ID (from the database, after the insert) in order to proceed with logicB. That's why I am doing 2 save changes. The first one in order to get the userID.

I added a Transaction, because sometimes, LogicB might throw an exception, and if that happens, I want to rollback the changes done (remove the user from the db)

That logic is working correctly, however I have a question:

Lets say 2 requests has been made at the same time, and this specific scenario happens:

Request 1 and Request 2 arrive at the same exact time

Scenario:

Request 1 Do LogicA, Insert user1 and save changes

Request 2 Do LogicA, Insert user2 and save changes

Request 1 Get Id for user1, Do LogicB, exception happens, Rollback the changes by removing user1, returns null

Request 2 Get Id for user2, Do LogicB, LogicB does NOT throw an exception, all is fine, returns user2

Since it is very hard to reproduce this scenarion, I want to ask about something that is worrying me:

Finally, the question :)

If the request to insert user 1 fails, but user 2 succeed, Would the database ID of user2 change? (because user1 got deleted when I rolled back) did user 2 change his ID to adapt to the rollback that happened in the other request, or did he remain the same ID that was assigned at first? (His database ID I mean)

I hope I was clear Thanks for any clarifications,

usr usr · Accepted Answer · 2015-02-07T22:00:09

I assume the "database ID" is an IDENTITY column in SQL Server. Identity numbers are not part of a transaction ever. They are drawn independently.

IDs never change after having been generated. ID gaps are also possible in the rollback case (and others).

IDs are not guaranteed to be contiguous. They are just counters.

Does EF Transaction rollback have an effect on other requests that arrives at the same time?

Scenario:

1 Answers