Date: Mon, 16 Mar 2026 17:52:38 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Corey Huinker <corey.huinker@gmail.com>,
	Sami Imseih <samimseih@gmail.com>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: Add starelid, attnum to pg_stats and leverage this in pg_dump
Message-ID: <abiJtpb6FsluRpGk@nathan>
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On Tue, Mar 17, 2026 at 06:49:17AM +0900, Michael Paquier wrote:
> On Mon, Mar 16, 2026 at 03:15:14PM -0500, Nathan Bossart wrote:
>> On Mon, Mar 16, 2026 at 04:04:23PM -0400, Corey Huinker wrote:
>>> expr_attnum was something that Michael Paquier had lamented that the view
>>> didn't have. There is obviously no present need for it, as pg_dump isn't
>>> being modified for extended stats at all.
>> 
>> Okay.  I think I'll continue to leave this one out for now.
> 
> Lamenting is the right term.  The expressions stored in an extended
> stats object have attnumbers computed by the backend, starting from -1
> and decremented, and we don't expose this information at all in any
> system view.  It could have helped in enforcing a stronger ordering of
> the items dumps for the extstats restore functions.  I still think
> that it could provide an extra layer of safety.  Now, we don't
> critically require it either based on how we pass down the input
> arrays, how we dump the data from the catalogs, and how we treat the
> order of the items given as function args.

FTR I'm not mortally opposed to the idea.  I just want to get the easier
stuff out of the way first so we can commit the pg_dump change.  Then we
can give expr_attnum our undivided attention.

-- 
nathan