Re: Possible to create canonicalized range type without being superuser?

On Tue, Jul 5, 2016 at 5:37 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Paul Jungwirth <pj(at)illuminatedcomputing(dot)com> writes:
> > The problem is this (tried on 9.3 and 9.5):
> > db=> create type inetrange;
> > ERROR: must be superuser to create a base type
> > So I'm wondering whether there is any way around this circle without
> > being a superuser?
>
> The only other obvious way to deal with this is to allow the canonical
> function to be defined after the range type is created, and then added to
> the type via an ALTER TYPE command. But then you have an interval where
> the type is not restricted, in which you might store values that aren't
> canonical.
>

​Can the canonical function be definitionally optional but runtime
required? That is, have it only be an error to use a type lacking a
canonical function? If so I think a usable idiom is that for types that
don't want to canonicalize (i.e., presently have a NULL assigned) they
would make an explicit declaration by doing something like:

CREATE TYPE int4range AS RANGE (subtype = int4, canonical = int4_identity);

Now you have a window where the type is incompletely defined and when the
missing canonical function is encountered the system balks. At some future
point a function can be associated via ALTER TYPE which makes the type
completely defined.

CREATE TYPE inetrange AS RANGE (subtype = inet, canonical = NULL);
ALTER TYPE inetrange SET PROPERTY canonical = inet_canonicalizer;
​
David J.