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

Hello,

I believe I may have found a regression in PostgreSQL 19devel, downloaded
on 2026-04-09
from https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.gz.

postgres=# select version();
version
-----------------------------------------------------------------------------------------------------
PostgreSQL 19devel on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu
13.2.0-23ubuntu4) 13.2.0, 64-bit

With the reproducer below, PostgreSQL 18 reports a normal foreign-key
violation
at INSERT time, but PostgreSQL 19devel instead throws an internal-looking
error:

ERROR: operator 98 is not a member of opfamily 1976

-- reproducer:
drop table if exists parent, child;

create table parent (
app_id varchar(256) not null,
report_id smallint not null,
otype integer not null,
subtype integer not null,
ctype integer not null,
column_name varchar(30) not null,
primary key (app_id, report_id, otype, subtype, ctype, column_name)
);

create table child (
app_id varchar(256) not null,
report_id smallint not null,
otype integer not null,
subtype integer not null,
column_name varchar(30) not null,
ctype integer,
-- intentionally swapped: column_name, ctype
constraint child_fk
foreign key (app_id, report_id, otype, subtype, column_name, ctype)
references parent (app_id, report_id, otype, subtype, column_name,
ctype)
);

-- trigger the problem
insert into child (app_id, report_id, otype, subtype, column_name, ctype)
values ('DEFAULT_APP', 0, -1, -1, 'ID', -1);

/Fredrik Widlert
fredrik(dot)widlert(at)digpro(dot)se