Re: column ordering, was Re: [PATCHES] Enums patch v2

On Thu, Dec 21, 2006 at 11:15:38AM -0500, Tom Lane wrote:
> Martijn van Oosterhout <kleptog@svana.org> writes:
> > Can we? For anything of any permenence (view definitions, rules,
> > compiled functions, plans, etc) you're going to want the physical
> > number, for the same reason we store the oids of functions and tables.
>
> Not if we intend to rearrange the physical numbers during column
> add/drop to provide better packing.

Urk! If that's what people are suggesting, I'd run away very quickly.
Getting better packing during table create is a nice idea, but
preserving it across add/drop column is just... evil.

Run CLUSTER is you want that, I was expecting add/drop to be a simple
catalog change, nothing more.

> You could make a case that we need *three* numbers: a permanent column
> ID, a display position, and a storage position.

That's just way too complicated IMHO. It add's extra levels of
indirection all over the place.

I was envisiging the physical number to be fixed and immutable (ie
storage position = permanent position).

Have a nice day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.