Re: RFC: Restructuring pg_aggregate

Bruce Momjian wrote:
>
> Hiroshi Inoue wrote:
> > Tom Lane wrote:
> >
> > > Hiroshi's "DROP_COLUMN_HACK" was essentially along this line, but
> > > I think he made a representational mistake by trying to change the
> > > attnums of dropped columns to be negative values.
> >
> > Negative attnums had 2 advantages then. It had a big
> > advantage that initdb isn't needed. Note that it was
> > only a trial hack and there was no consensus on the way.
> > It was very easy to change the implementation to use
> > attisdropped. OTOH physical/logical attnums approach
> > needed the change on pg_class, pg_attribute and so
> > I've never had a chance to open the patch to public.
> > It was also more sensitive about oversights of needed
> > changes than the attisdropped flag approach.
> >
> > > That means that
> > > a lot of low-level places *do* need to know about the dropped-column
> > > convention, else they can't make any sense of tuple layouts.
> >
> > Why ? As you already mentioned, there were not that many places
> > to be changed.
> >
> > Well what's changed since then ?
>
> Here is an old email from me that outlines the idea of having a
> physical/logical attribute numbering system, and the advantages.

I already tried physical/logical attribute implementation
pretty long ago. Where are new ideas to solve the problems
that the approach has ?

regards,
Hiroshi Inoue