Date: Sun, 25 Apr 2021 15:40:40 -0400
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Sven Klemm <sven@timescale.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Fix dropped object handling in pg_event_trigger_ddl_commands
Message-ID: <20210425194040.GA11244@alvherre.pgsql>
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On 2021-Apr-25, Sven Klemm wrote:

> On Sun, Apr 18, 2021 at 2:12 PM Sven Klemm <sven@timescale.com> wrote:
> > when creating an event trigger for ddl_command_end that calls
> > pg_event_trigger_ddl_commands certain statements will cause the
> > trigger to fail with a cache lookup error. The error happens on
> > master, 13 and 12 I didnt test any previous versions.
> >
> > trg=# ALTER TABLE t ALTER COLUMN f1 SET DATA TYPE bigint, ALTER COLUMN
> > f1 DROP IDENTITY;
> > ERROR: XX000: cache lookup failed for relation 13476892
> > CONTEXT: PL/pgSQL function ddl_end() line 5 at FOR over SELECT rows
> > LOCATION: getRelationTypeDescription, objectaddress.c:4178
> 
> Any opinions on the patch? Is this not worth the effort to fix or is
> there a better way to fix this?

Hello, I haven't looked at this but judging from the general shape of
function and error message, it seems clearly a bug that needs to be
fixed somehow.  I'll try to make time to look at it sometime soon, but I
have other bugs to investigate and fix, so it may be some time.

I fear your proposal of ignoring the object may be the best we can do,
but I don't like it much.

-- 
Álvaro Herrera                            39°49'30"S 73°17'W
"La verdad no siempre es bonita, pero el hambre de ella sí"