Date: Mon, 16 Nov 2020 14:55:16 -0600
From: Justin Pryzby <pryzby@telsasoft.com>
To: Stephen Frost <sfrost@snowman.net>
Cc: Magnus Hagander <magnus@hagander.net>, Tom Lane <tgl@sss.pgh.pa.us>,
	Peter Eisentraut <peter.eisentraut@enterprisedb.com>,
	Heikki Linnakangas <hlinnaka@iki.fi>,
	Ian Lawrence Barwick <barwick@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: [PATCH] remove deprecated v8.2 containment operators
Message-ID: <20201116205516.GM14024@telsasoft.com>
References: <20201027032511.GF9241@telsasoft.com>
 <155ecfd8-7ac6-1875-5090-d79a586a8847@enterprisedb.com>
 <235561.1605220100@sss.pgh.pa.us>
 <CABUevEyLtOAPtY3MYap0b6H23WmsrGHmFN6On6v7CDi14FORDw@mail.gmail.com>
 <20201113150343.GT16415@tamriel.snowman.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20201113150343.GT16415@tamriel.snowman.net>
User-Agent: Mutt/1.9.4 (2018-02-28)
Precedence: bulk

On Fri, Nov 13, 2020 at 10:03:43AM -0500, Stephen Frost wrote:
> * Magnus Hagander (magnus@hagander.net) wrote:
> > On Thu, Nov 12, 2020 at 11:28 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > > > The changes to the contrib modules appear to be incomplete in some ways.
> > > >   In cube, hstore, and seg, there are no changes to the extension
> > > > scripts to remove the operators.  All you're doing is changing the C
> > > > code to no longer recognize the strategy, but that doesn't explain what
> > > > will happen if the operator is still used.  In intarray, by contrast,
> > > > you're editing an existing extension script, but that should be done by
> > > > an upgrade script instead.
> > >
> > > In the contrib modules, I'm afraid what you gotta do is remove the
> > > SQL operator definitions but leave the opclass code support in place.
> > > That's because there's no guarantee that users will update the extension's
> > > SQL version immediately, so a v14 build of the .so might still be used
> > > with the old SQL definitions.  It's not clear how much window we need
> > > give for people to do that update, but I don't think "zero" is an
> > > acceptable answer.
> > 
> > Based on my experience from the field, the answer is "never".
> > 
> > As in, most people have no idea they are even *supposed* to do such an
> > upgrade, so they don't do it. Until we solve that problem, I think
> > we're basically stuck with keeping them "forever". (and even if/when
> > we do, "zero" is probably not going to cut it, no)
> 
> Yeah, this is a serious problem and one that we should figure out a way
> to fix or at least improve on- maybe by having pg_upgrade say something
> about extensions that could/should be upgraded..?

I think what's needed are:

1) a way to *warn* users about deprecation.  CREATE EXTENSION might give an
elog(WARNING), but it's probably not enough.  It only happens once, and if it's
in pg_restore/pg_upgrade, it be wrapped by vendor upgrade scripts.  It needs to
be more like first function call in every session.  Or more likely, put it in
documentation for 10 years.

2) a way to *enforce* it, like making CREATE EXTENSION fail when run against an
excessively old server, including by pg_restore/pg_upgrade (which ought to also
handle it in --check).

Are there any contrib for which (1) is done and we're anywhere near doing (2) ?

-- 
Justin