Re: Add pg_basetype() function to obtain a DOMAIN base type

Tomas Vondra <tomas.vondra@enterprisedb.com> writes:
> On 2/17/24 01:57, jian he wrote:
>> On Sat, Feb 17, 2024 at 2:16 AM Tomas Vondra
>> <tomas.vondra@enterprisedb.com> wrote:
>>> 1) We already have pg_typeof() function, so maybe we should use a
>>> similar naming convention pg_basetypeof()?

>> I am ok with pg_basetypeof.

> An alternative approach would be modifying pg_typeof() to optionally
> determine the base type, depending on a new argument which would default
> to "false" (i.e. the current behavior).

Forgive me for not having read the thread, but I wonder why we want
this to duplicate the functionality of pg_typeof() at all.  My first
reaction to the requirement given in the thread subject is to write
a function that takes a type OID and returns another type OID
(or the same OID, if it's not a domain).  If you want to determine
the base type of some namable object, you could combine the functions
like "basetypeof(pg_typeof(x))".  But ISTM there are other use cases
where you'd have a type OID.  Then having to construct an object to
apply a pg_typeof-like function to would be difficult.

I don't have an immediate proposal for exactly what to call such a
function, but naming it by analogy to pg_typeof would be questionable.

            regards, tom lane