Re: Foreign key validation failure in 18beta1

On Wed, May 28, 2025 at 8:38 PM Tender Wang <tndrwang@gmail.com> wrote:
>
>
>
> Alvaro Herrera <alvherre@alvh.no-ip.org> 于2025年5月28日周三 20:26写道：
>>
>> On 2025-May-28, Tender Wang wrote:
>>
>> > I dided the codes, in QueueFKConstraintValidation(),  we add three
>> > newconstraint for the
>> > fk rel, because the pk rel is partition table.
>> >
>> > During phase 3 of AlterTable, in ATRewriteTables(),
>> > call validateForeignKeyConstraint() three times.
>> > The first time the pk rel is pk, and it's ok.
>> > The second time the pk rel is only pk_1, and the type(1) is not in pk_1, so
>> > an error is reported.
>> >
>> > In this case, the two children newconstraint  should not be added to the
>> > queue.
>>
>> Yeah, I reached the same conclusion and this is the preliminary fix I
>> had written for it.  I don't like that I had to duplicate a few lines of
>> code, but maybe it's not too bad.  Also the comments need to be
>> clarified a bit more.
>
>
> If the child table is still a partitioned table, the patch seems not work.
>
> I figure out a quick fix as the attached. I add a bool argument into the QueueFKConstraintValidation().
> If it is true, it means we recursively call QueueFKConstraintValidation(), then we don't add the newconstraint to the
queue. 
>
> I'm not sure about this fix. Any thoughts?

it will fail for the following case:

begin;
drop table if exists fk;
drop table if exists pk;
create table pk(i int primary key);
insert into pk values (0), (1);
create table fk(i int) partition by range (i);
create table fk_1 partition of fk for values from (0) to (1);
create table fk_2 partition of fk for values from (1) to (3);
insert into fk values (1),(2);
alter table fk add foreign key(i) references pk not valid;
commit;
alter table fk validate constraint fk_i_fkey; --error, should fail.

-----------
The attached *draft* patch is based on your idea.

The idea is that we only need to conditionally do
``tab->constraints = lappend(tab->constraints, newcon);`` within
QueueFKConstraintValidation.
but the catalog update needs to be done recursively.