Duplicate OIDs on Postgres ≥14

[lacanoid]

Regression tests fail on PG 15. It seems that same OIDs are used for several distinct catalog objects, causing ddlx to dump a wrong object.

Investigate further and report to pgsql-hackers if necessary.

[lacanoid]

create or replace function crossoidcount(oid,oid) returns bigint language plpgsql as 
$$
declare s text; n bigint;
begin 
 s := format('select count(*) from %I a join %I b using (oid)',$1::regclass,$2::regclass);
 execute s into n; 
 return n;
end
$$;

with a as (
select attrelid::regclass as oid
  from pg_catalog.pg_attribute a 
  join pg_class c on (c.oid=attrelid)
 where c.relkind='r' and attname='oid' and atttypid='oid'::regtype
 order by attrelid
)
select *,crossoidcount(a1.oid,a2.oid) from a a1
  join a a2 on (a1.oid<a2.oid)
 where crossoidcount(a1.oid,a2.oid)>0
 order by 1,2;

[lacanoid]

Postgres 13 and earlier

 oid | oid | crossoidcount 
-----+-----+---------------
(0 rows)

Postgres 14

    oid    |    oid     | crossoidcount 
-----------+------------+---------------
 pg_amop   | pg_amproc  |           697
 pg_amop   | pg_cast    |           230
 pg_amop   | pg_opclass |           164
 pg_amproc | pg_cast    |           230
 pg_amproc | pg_opclass |           164
 pg_cast   | pg_opclass |           164
(6 rows)

Postgres 15

      oid      |      oid      | crossoidcount 
---------------+---------------+---------------
 pg_type       | pg_amop       |           115
 pg_type       | pg_amproc     |           115
 pg_type       | pg_cast       |           115
 pg_type       | pg_opclass    |           115
 pg_amop       | pg_amproc     |           697
 pg_amop       | pg_cast       |           229
 pg_amop       | pg_constraint |           109
 pg_amop       | pg_opclass    |           164
 pg_amproc     | pg_cast       |           229
 pg_amproc     | pg_constraint |           109
 pg_amproc     | pg_opclass    |           164
 pg_cast       | pg_constraint |           109
 pg_cast       | pg_opclass    |           164
 pg_constraint | pg_opclass    |            49
(14 rows)

Postgres 16

       oid       |      oid      | crossoidcount 
-----------------+---------------+---------------
 pg_type         | pg_amop       |           115
 pg_type         | pg_amproc     |           115
 pg_type         | pg_cast       |           115
 pg_type         | pg_opclass    |           115
 pg_auth_members | pg_amop       |             3
 pg_auth_members | pg_amproc     |             3
 pg_auth_members | pg_cast       |             3
 pg_amop         | pg_amproc     |           697
 pg_amop         | pg_cast       |           229
 pg_amop         | pg_constraint |           110
 pg_amop         | pg_opclass    |           164
 pg_amproc       | pg_cast       |           229
 pg_amproc       | pg_constraint |           110
 pg_amproc       | pg_opclass    |           164
 pg_cast         | pg_constraint |           110
 pg_cast         | pg_opclass    |           164
 pg_constraint   | pg_opclass    |            49
(17 rows)