Re: WIP: Rework access method interface

Petr Jelinek <petr@2ndquadrant.com> writes:
> On 2015-08-10 16:58, Alexander Korotkov wrote:
>> That should work, thanks! Also we can have SQL-visible functions to get
>> amsupport and amstrategies and use them in the regression tests.

> SQL-visible functions would be preferable to storing it in pg_am as
> keeping the params in pg_am would limit the extensibility of pg_am itself.

I don't see any particularly good reason to remove amsupport and
amstrategies from pg_am.  Those are closely tied to the other catalog
infrastructure for indexes (pg_amproc, pg_amop) which I don't think are
candidates for getting changed by this patch.

There are a couple of other pg_am columns, such as amstorage and
amcanorderbyop, which similarly bear on what's legal to appear in
related catalogs such as pg_opclass.  I'd be sort of inclined to
leave those in the catalog as well.  I do not see that exposing
a SQL function is better than exposing a catalog column; either
way, that property is SQL-visible.