Re: btree index and max()

Bruce Momjian wrote:
>
> > leonbloy@sinectis.com.ar wrote:
> > >
> > > => explain select max(rid) from facturas;
> > > NOTICE:  QUERY PLAN:
> > >
> > > Aggregate  (cost=21139.66 rows=342414 width=4)
> > >   ->  Seq Scan on facturas  (cost=21139.66 rows=342414 width=4)
> > >
> > > I understand that the query planner cannot be so clever
> > > to grasp that this particular function (max or min)
> > > might be evaluated by just travelling the BTREE index.
> > > Am I correct?
> >
> > I believe you are unfortunately correct.  :(
>
> That would be a good optimization.  Let me add it to the TODO list.
> Much better than trying to keep the max stored somewhere.

There was a lot of discussion about this on the hackers list recently,
but I don't recall the outcome.

Regards,
Ed Loehr