Re: BUG #17886: Error disabling user triggers on a partitioned table

PG Bug reporting form <noreply@postgresql.org> writes:
> result:
> postgres=# alter table public.test DISABLE TRIGGER USER;
> ERROR:  42704: trigger "trigger_test" for table "test_def" does not exist
> LOCATION:  EnableDisableTriggerNew, trigger.c:1658

> Expected Result (Postgresql 15.2 and 14.4 - fine):
> testdb=> alter table public.test DISABLE TRIGGER USER;
> ALTER TABLE

Commit ec0925c22 seems to have been quite snakebit.  I already fixed
a deficiency in it in v15/HEAD, but here we have a different symptom
in the older branches.  What's happening is that EnableDisableTrigger
is ignoring the child trigger because it has tgisinternal set to true
and the command passes skip_system = true.

I'm inclined to think that in the older branches (pre f4566345c)
we need to do

-       if (oldtrig->tgisinternal)
+       if (oldtrig->tgisinternal && !OidIsValid(oldtrig->tgparentid))
        {
            /* system trigger ... ok to process? */

but I've not tested that.  Alvaro, what do you think?

            regards, tom lane