Re: SAVEPOINT and FOR UPDATE

On Fri, 2006-08-04 at 18:01, Gregory Stark wrote:
> Tom Lane <tgl@sss.pgh.pa.us> writes:
>
> > "Thomas F. O'Connell" <tfo@sitening.com> writes:
> > > I sort of expected the release of the savepoint to be tantamount to a
> > > commit of the subtransaction, but it doesn't appear to have been.
> >
> > But you still haven't committed the outer transaction: rolling it back
> > must undo the effects of the subtransaction, no?  So a "release" merely
> > destroys the separate identity of the subtransaction and assigns all its
> > effects (including locks) to the parent transaction.
>
> There seems to be a recurring confusion between subtransactions and autonomous
> transactions. Perhaps there should be a caveat in the SAVEPOINT documentation
> explaining that they aren't autonomous transactions and the work inside the
> savepoint is still subject to the regular transaction semantics for the
> outermost transaction and isn't actually committed until the outer transaction
> commits.

Note that one CAN get autonomous transactions using dblink.  I've used
it once or twice in the past to do that.