Re: Hmm, nodeUnique doesn't really support backwards scan too well

On Tue, 2008-08-05 at 18:00 -0500, Jaime Casanova wrote:
> On 8/5/08, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> > > I've never seen anyone scan backwards like this at all in practical use.
> >
> > > I knew it was possible, but never seen it done.
> >
> > > It seems entirely probable nobody else has either. It's a PostgreSQL
> > > extension, so people arriving from outside don't even know it exists,
> >
> > Say again? Both the SCROLL option to DECLARE CURSOR and FETCH PRIOR are
> > straight out of the SQL92 spec.

Yep. I was talking about FETCH BACKWARDS n | ALL
though forgot that this is the same thing as FETCH PRIOR.

But even use of FETCH PRIOR is fairly rare, so IMHO your proposal is
still safe.

> i think Simon is talking about DISTINCT ON

No, don't confuse things!

That is rare also, but I know of various places that is used.

--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support