Re: BUG #12330: ACID is broken for unique constraints

On Mon, Dec 29, 2014 at 9:09 AM, Kevin Grittner <kgrittn@ymail.com> wrote:
> Merlin Moncure <mmoncure@gmail.com> wrote:
>> In other words, the current behavior is:
>> txn A,B begin
>> txn A inserts
>> txn B inserts over A, locks, waits
>> txn A commits.  B aborts with duplicate key error
>
> What I'm proposing is that for serializable transactions B would
> get a serialization failure; otherwise B would get a duplicate key
> error.  If the retry of B looks at something in the database to
> determine what it's primary key should be it will get a new value
> on the retry, since it will be starting after the commit of A.  If
> it is using a literal key, not based on something changed by A, it
> will get a duplicate key error on the retry, since it will be
> starting after the commit of A.
>
> It will either succeed on retry or get an error for a different
> reason.

In that case: we don't agree.  How come duplicate key errors would be
reported as serialization failures but not RI errors (for example,
inserting a record pointing to another record which a concurrent
transaction deleted)?

IMO, serialization errors are an implementation artifact and should
not mask well defined errors in SQL under any circumstances (or if
they must, those cases should absolutely be as narrow as possible).

merlin