Re: nested xacts and phantom Xids

I said

> I'll post a full patch once the missing deferred trigger stuff works.
> With the patches I posted to inval.c I think this fulfills the
> requirements, barring the performance issues raised.

Ok, here is a full patch that includes:

- all what was in the previous patch
- GUC vars are rolled back on subxact abort
- the inval msg lists are cleaned up of items created in the aborting
subxact
- SET CONSTRAINTS is rolled back too

Missing:

- all the other items Tom mentioned in his last mail, including
performance enhancements.

- discussion whether we want a different syntax for subxacts, like
SUBBEGIN/SUBCOMMIT/SUBABORT instead of BEGIN/COMMIT/ABORT. Please
comment on this point.

- support for SAVEPOINT syntax.

--
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"La grandeza es una experiencia transitoria. Nunca es consistente.
Depende en gran parte de la imaginación humana creadora de mitos"
(Irulan)