Re: BEGIN inside transaction should be an error

On 5/12/06, Mario Weilguni <mweilguni(at)sime(dot)com> wrote:
> Am Donnerstag, 11. Mai 2006 22:16 schrieb Simon Riggs:
> > On Wed, 2006-05-10 at 21:24 -0400, Tom Lane wrote:
> > > Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
> > > > How do other database deal with this? Either they nest BEGIN/COMMIT or
> > > > they probably throw an error without aborting the transaction, which is
> > > > pretty much what we do. Is there a database that actually aborts a
> > > > whole transaction just for an extraneous begin?
> > >
> > > Probably not. The SQL99 spec does say (in describing START TRANSACTION,
> > > which is the standard spelling of BEGIN)
> > >
> > > 1) If a <start transaction statement> statement is executed when
> > > an SQL-transaction is currently active, then an exception condition is
> > > raised: invalid transaction state - active SQL-transaction.
> > >
> > > *However*, they are almost certainly expecting that that condition only
> > > causes the START command to be ignored; not that it should bounce the
> > > whole transaction. So I think the argument that this is required by
> > > the spec is a bit off base.
> >
> > If you interpret the standard that way then the correct behaviour in the
> > face of *any* exception condition should be *not* abort the transaction.
> > In PostgreSQL, all exception conditions do abort the transaction, so why
> > not this one? Why would we special-case this?
>
> IMO it's ok to raise an exception - if this is configurable for at least one
> releasy cycle - giving developers time to fix applications. It's no good
> behaviour to change something like this without any (at least time-limited )
> backward compatible option.
>

if an option to change it is put in place, maybe it will be there
forever (with a different default behavior)...

i am all in favor of a second begin to throw an exception "already in
transaction" or something else
(http://archives.postgresql.org/pgsql-hackers/2005-12/msg00813.php)
but if we do it we should do it the only behavior... i don't think
it's good to introduce a new GUC for that things (we will finish with
GUCs to turn off every fix)

--
regards,
Jaime Casanova

"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs and the universe trying
to produce bigger and better idiots.
So far, the universe is winning."
Richard Cook