From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jeff Davis <pgsql@j-davis.com>
cc: Corey Huinker <corey.huinker@gmail.com>,
        Andres Freund <andres@anarazel.de>,
        Michael Paquier <michael@paquier.xyz>,
        jian he <jian.universality@gmail.com>,
        Nathan Bossart <nathandbossart@gmail.com>,
        Bruce Momjian <bruce@momjian.us>,
        Matthias van de Meent <boekewurm+postgres@gmail.com>,
        Magnus Hagander <magnus@hagander.net>,
        Stephen Frost <sfrost@snowman.net>,
        Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>,
        Peter Smith <smithpb2250@gmail.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
        alvherre@alvh.no-ip.org
Subject: Re: Statistics Import and Export
In-reply-to: <6d1c72b06fe3645a50897381d71ff1b39085abf6.camel@j-davis.com>
References: <sdno5atrplq5b67vcx7x6fkzevwkzojd23izbguy2yma424wmp@siwbi3ijxdxs> <x5yo5ly5u3dhzfaq3hrzeqhju3io5zmwk4yqrkge3ywcflffck@ghbbgsfv56yb> <3670503.1740173078@sss.pgh.pa.us> <blezfpeafycxlizyynwvwzh2vywmklhvfqudhicjrccu4raqpx@4ttfufowc2vo> <3728741.1740178078@sss.pgh.pa.us> <CADkLM=f0a43aTd88xW4xCFayEF25g-7hTrHX_WhV40HyocsUGg@mail.gmail.com> <97b451228227c555be1a4f79c4a62ddec9a74f06.camel@j-davis.com> <CADkLM=ckXu5wzSQZ3Y_fvAaL8rZ+upZdSecBLf5FCTMj7M6T-A@mail.gmail.com> <b227c4fca29dfb893bb414ce6d84fc2377489ecc.camel@j-davis.com> <CADkLM=dRMC6t8gp9GVf6y6E_r5EChQjMAAh_vPyih_zMiq0zvA@mail.gmail.com> <y2d36zf6pl3n6ni6e4ctblu3a5iazi2dycknq53h2mjvp7lto4@hhww3h2qgdrw> <1457469.1740419458@sss.pgh.pa.us> <CADkLM=eWSv2z_DVB=psfwHitq7DbFJQaP9A46R27eARC-4OYtQ@mail.gmail.com> <6d1c72b06fe3645a50897381d71ff1b39085abf6.camel@j-davis.com>
Comments: In-reply-to Jeff Davis <pgsql@j-davis.com>
	message dated "Mon, 24 Feb 2025 10:54:43 -0800"
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Date: Mon, 24 Feb 2025 14:34:13 -0500
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Jeff Davis <pgsql@j-davis.com> writes:
> We certainly want attnames for tables to keep it working reasonably
> well for cases where the user might be doing something more interesting
> than a binary upgrade, as you point out. But attribute numbers for
> indexes seem much more reliable: an index with a different attribute
> order is a fundamentally different index.

Right.  We went through pretty much this reasoning, as I recall,
when we invented ALTER INDEX ... SET STATISTICS.  The original
version used a column name like ALTER TABLE did, and we ran into
exactly the present problem that the names aren't too stable across
dump/restore, and we decided that index column numbers would do
instead.  You can't add or drop a column of an index, nor redefine it
meaningfully, except by dropping the whole index which will make any
associated stats go away.

The draft patch I posted allows callers to use attname or attnum
at their option, because I didn't see a reason to restrict that.
But I envisioned that pg_dump would always use attname for table
columns and attnum for index columns.

			regards, tom lane