Re: Constraint's NO INHERIT option is ignored in CREATE TABLE LIKE statement

On Wed, Feb 19, 2020 at 4:02 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Ildar Musin <ildar(at)adjust(dot)com> writes:
> > My colleague Chris Travers discovered something that looks like a bug.
> > Let's say we have a table with a constraint that is declared as NO
> INHERIT.
> > ...
> > Now when we want to make a copy of the table structure into a new table
> > the `NO INHERIT` option is ignored.
>
> Hm, I agree that's a bug, since the otherwise-pretty-detailed CREATE TABLE
> LIKE documentation makes no mention of such a difference between original
> and cloned constraint.
>
> However, I'd be disinclined to back-patch, since it's barely possible
> somebody out there is depending on the existing behavior.
>

Not sure I agree with the premise that it is not supposed to be copied; is
there some other object type the allows NO INHERIT that isn't copied when
CREATE TABLE LIKE is used and check constraints are the odd ones out?

Inheritance is what NO INHERIT is about and CREATE TABLE LIKE pointedly
doesn't setup an inheritance structure. The documentation seems ok since
saying that NO INHERIT is ignored when inheritance is not being used seems
self-evident. Sure, maybe some clarity here could be had, but its not like
this comes up with any regularity.

David J.