Fabien COELHO <coelho@cri.ensmp.fr> writes:
> I'm wondering for the rationnal of the types used in various tables in
> pg_catalog (v 7.4.2) so as to represent the very same thing:
History and backwards compatibility, mostly.
From the standpoint of the backend I don't think there is any
fundamental reason why we couldn't change pg_index.indkey and indclass
into varlena arrays, but I'd be worried about breaking existing
client-side code that looks at those columns. In particular the
question of whether indexing starts at 0 or 1 would be nasty.
regards, tom lane