实体框架可序列化事务死锁

Question

I have to insert a row into the database but the problem is that the primary key is generated based on the total counts of rows. Eg if the db has 25601 rows, the ID of the newly inserted record would be CT25602.

I want to use transactions for primary key collisions. Here is the code I wrote.

public void CreateContact(ContactViewModel input)
{
    var transactionScopeOptions = new TransactionOptions
    {
        IsolationLevel = IsolationLevel.Serializable,
        Timeout = TimeSpan.MaxValue
    };

    using (TransactionScope transaction = new TransactionScope(TransactionScopeOption.Required, transactionScopeOptions))
    {
        var contactNo = GenerateIdentity();
        var contact = MapContactFields(new NavContact { No_ = contactNo }, input);

        _db.Contacts.InsertOnSubmit(contact);
        _db.SubmitChanges();
        transaction.Complete();
    }
}

This code gives me deadlocks if two persons are trying to insert a contact in a small timespan.

Any suggestions ? Thank you

Answer 1

Yes, the scenario you described is very likely to deadlock. I would recommend using a sequence instead. If not, then one solution is to acquire an exclusive app lock in the transaction, before scannig for the next identity. See sp_getapplock .