Transactionscope and deadlocks when using enterprise library

Question

We are using Enterprise Library for data access.

One of our methods has a delete and then an insert, against the same table. This gives a deadlock.

If we put these inside a transaction scope the deadlock no longer occurs.

Intuitively, it feels like it should be the opposite way around. Can anyone explain why it works like this?

Answer 1

Transaction scope combined with TransactionOptions IsolationLevel = IsolationLevel.ReadUncommitted is equivalent to WITH(NOLOCK) in T-SQL so if the table is not locked the deadlocks don't occur...

using (var scope = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions(){ IsolationLevel = IsolationLevel.ReadUncommitted }))
{
}