pw <p.willis@telus.net> writes:
> I have a table with a serial type in it as a record id.
> The type of this object comes back as int4 when I query via
> pg_type.
> How can I distinguish this counter type from just a plain int4?
Well, you can't, because serial isn't actually a type in Postgres.
As the manual tries to explain, serial is just a shorthand for creating
an integer column whose default is a nextval() call on a sequence.
So the way to tell is to look for a default expression of that kind.
regards, tom lane