Date: Wed, 9 Jun 2021 09:55:08 -0400
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Michael Paquier <michael@paquier.xyz>
Cc: Aleksander Alekseev <aleksander@timescale.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
	Sven Klemm <sven@timescale.com>
Subject: Re: Fix dropped object handling in pg_event_trigger_ddl_commands
Message-ID: <202106091355.sphciftmvqds@alvherre.pgsql>
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On 2021-Jun-09, Michael Paquier wrote:

> On Mon, Jun 07, 2021 at 12:44:42PM +0300, Aleksander Alekseev wrote:
> > I confirm that the bug still exists in master (be57f216). The patch
> > fixes it and looks good to me. I changed the wording a little and
> > added a regression test. The updated patch is in the attachment. I
> > added this thread to the CF and updated the status to "Ready for
> > Committer".
> 
> FWIW, that looks rather natural to me to me to just ignore the object
> if it has already been dropped here.  The same kind of rules apply to
> tables dropped  with DROP TABLE which would not show up as of
> pg_event_trigger_ddl_commands(), but one can get a list as of
> pg_event_trigger_dropped_objects().

Oh, that parallel didn't occur to me.  I agree it seems a useful
precedent.

> Alvaro, were you planning to look at that?  I have not looked at the
> patch in details.  

I have it on my list of things to look at, but it isn't priority.  If
you to mess with it, please be my guest.

> missing_ok is available in getObjectIdentity() only
> since v14, so this cannot be backpatched :/

Ooh, yeah, I forgot about that.  And that one was pretty invasive ...

I'm not sure if we can reasonably implement a fix for older releases.
I mean, it's a relatively easy test: do a syscache search for the object
or a catalog indexscan (easy to do with get_object_property_data-based
API), and if the object is gone, skip getObjectTypeDescription and
getObjectIdentity.  But maybe this is too much code to add to stable
releases ...

-- 
Álvaro Herrera       Valdivia, Chile