Re: Dumping/restoring fails on inherited generated column

Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> writes:
> On 2021-01-29 17:41, Tom Lane wrote:
>> However ... this doesn't solve all the cases noted in this thread.
>> In the first example I gave at [1],
>> d3=# create table parent (f1 int default 2);
>> CREATE TABLE
>> d3=# create table child (f1 int default 3) inherits(parent);
>> NOTICE: merging column "f1" with inherited definition
>> CREATE TABLE
>> d3=# create table child2() inherits(parent);
>> CREATE TABLE
>> d3=# alter table child2 alter column f1 set default 42;
>> ALTER TABLE
>>
>> pg_dump still fails to restore child2.f1's non-inherited default.

> I can't tell what the problem is in this example. I tried with PG11,
> 12, and master, and the schema dump comes out with those same four
> commands and they restore correctly AFAICT.

Oh! Trying it now, I see that the child2 default does get restored
as a "separate default" object:

ALTER TABLE ONLY public.child2 ALTER COLUMN f1 SET DEFAULT 42;

This is a bit weird, because you'd think it would be handled
the same as the other child's default, but it isn't; that
one comes out as

CREATE TABLE public.child (
f1 integer DEFAULT 3
)
INHERITS (public.parent);

while child2 looks like

CREATE TABLE public.child2 (
)
INHERITS (public.parent);

I now suspect that I'd seen this dump of "child2" and missed the later
ALTER. So no bug here, just pilot error. Sorry for the noise.

regards, tom lane