R – Determine whether the transaction is DTC transaction or not when debugging

You could try shutting down the Distributed Transaction Cordinator service and setting its startup type to disabled. This will cause an exception when the transaction is promoted that will have the problem code in the call stack.

Of course this won't help if you have other items running on the machine that require this service, but would be possible on a debug machine.

With the Entity Framework most of the time SaveChanges() is sufficient. This creates a transaction, or enlists in any ambient transaction, and does all the necessary work in that transaction.

Sometimes though the SaveChanges(false) + AcceptAllChanges() pairing is useful.

The most useful place for this is in situations where you want to do a distributed transaction across two different Contexts.

I.e. something like this (bad):

using (TransactionScope scope = new TransactionScope())
{
    //Do something with context1
    //Do something with context2

    //Save and discard changes
    context1.SaveChanges();

    //Save and discard changes
    context2.SaveChanges();

    //if we get here things are looking good.
    scope.Complete();
}

If context1.SaveChanges() succeeds but context2.SaveChanges() fails the whole distributed transaction is aborted. But unfortunately the Entity Framework has already discarded the changes on context1, so you can't replay or effectively log the failure.

But if you change your code to look like this:

using (TransactionScope scope = new TransactionScope())
{
    //Do something with context1
    //Do something with context2

    //Save Changes but don't discard yet
    context1.SaveChanges(false);

    //Save Changes but don't discard yet
    context2.SaveChanges(false);

    //if we get here things are looking good.
    scope.Complete();
    context1.AcceptAllChanges();
    context2.AcceptAllChanges();

}

While the call to SaveChanges(false) sends the necessary commands to the database, the context itself is not changed, so you can do it again if necessary, or you can interrogate the ObjectStateManager if you want.

This means if the transaction actually throws an exception you can compensate, by either re-trying or logging state of each contexts ObjectStateManager somewhere.

See my blog post for more.