Subject: Re: \d with triggers: more than one row returned by a subquery used as an expression

From: Tom Lane <[email-masked]>
Date: Mon, 17 Jan 2022 17:02:00 -0500

Justin Pryzby <[email-masked]> writes:
> On Fri, Dec 17, 2021 at 09:43:56AM -0600, Justin Pryzby wrote:
>> I want to mention that the 2nd problem I mentioned here is still broken.
>> https://www.postgresql.org/message-id/[email-masked]
>> It happens if non-inheritted triggers on child and parent have the same name.

> This is the fix I was proposing
> It depends on pg_partition_ancestors() to return its partitions in order:
> this partition => parent => ... => root.

I don't think that works at all.  I might be willing to accept the
assumption about pg_partition_ancestors()'s behavior, but you're also
making an assumption about how the output of pg_partition_ancestors()
is joined to "pg_trigger AS u", and I really don't think that's safe.

ISTM the real problem is the assumption that only related triggers could
share a tgname, which evidently isn't true.  I think this query needs to
actually match on tgparentid, rather than taking shortcuts.  If we don't
want to use a recursive CTE, maybe we could define it as only looking up
to the immediate parent, rather than necessarily finding the root?

			regards, tom lane