Re: BUG: PostgreSQL 19devel throws internal opfamily error for FK with reordered referenced columns

On Fri, Apr 10, 2026 at 4:29 PM Fredrik Widlert
<fredrik(dot)widlert(at)digpro(dot)se> wrote:
> Thanks for the very quick fix - it's a great feeling to report a problem
> and get it fixed this quickly.

Credit goes to Matheus for quickly submitting a well-written patch.

> I can confirm that the fix solves not only the small reproducer but also
> the original problems I got when trying to install our (large) system
> on PostgreSQL 19 devel for testing.

Thanks for confirming that.

> We actually ran into the same problem in two ways:
> * the reordered FK with datatype mismatch (my reproducer)
> * other reordered FKs with the same datatypes, where we instead got
> regular FK violations
>
> In case you want a reproducer for the second case as well, I've included it below,
> but perhaps it's not relevant since the patch already fixed it.
>
> ----
> drop table if exists parent, child;
>
> create table parent (
> c1 integer,
> c2 integer,
> primary key (c1, c2)
> );
>
> create table child (
> c1 integer,
> c2 integer,
> constraint child_fk foreign key (c2, c1) references parent (c2, c1)
> );
>
> insert into parent (c1, c2) values (1, 2);
> insert into child (c1, c2) values (1, 2);

Good to know. It's worth adding this case next to the ones Matheus's
patch added, which the attached patch does. Will push it shortly.

--
Thanks, Amit Langote