Subject Re: [firebird-support] 2 identical record inserts not stopped by UNIQUE constraint
Author Ann W. Harrison
Bogusław Brandys wrote:

>> The first entry is the old version created by Transaction 1 which
>> is visible to Transaction 2, although it is actually deleted and
>> the delete is committed. The second entry is the row stored by
>> Transaction 2. In fact, the database is correct, but Transaction 2
>> has an incorrect view.
> Is it a bug or not a bug ?

Yes, it's a bug, and one that's older than many people on the list,
and it shows up in implementations of MVCC that Jim didn't write (as
well as all the ones he did!)