Re: [HACKERS] Surjective functional indexes

Greetings,

* Andres Freund (andres(at)anarazel(dot)de) wrote:
> On 2019-01-14 18:55:18 -0500, Stephen Frost wrote:
> > * Andres Freund (andres(at)anarazel(dot)de) wrote:
> > > > Or are you suggesting that pg_dump in v12+ would throw errors if it
> > > > finds that set? Or that we'll dump it, but fail to allow it into a
> > > > v12+ database? What if v12 sees "recheck_on_update='false'", as a v11
> > > > pg_dump might output today?
> > >
> > > It'll just error out on restore (including the internal one by
> > > pg_upgrade). I don't see much point in doing more, this isn't a widely
> > > used option by any stretch.
> >
> > This.. doesn't actually make sense. The pg_upgrade will use v12+
> > pg_dump. You're saying that the v12+ pg_dump will dump out the option,
> > but then the restore will fail to understand it?
>
> Why does that not make sense? With one exception the reloptions code in
> pg_dump doesn't have knowledge of individual reloptions. So without
> adding any special case code pg_dump will just continue to dump the
> option. And the server will just refuse to restore it, because it
> doesn't know it anymore.

Ugh, yeah, I was catching up to realize that we'd have to special-case
add this into pg_dump to get it avoided; most things in pg_dump don't
work that way.

As that's the case, then I guess I'm thinking we really should make
pg_upgrade complain if it finds it during the check phase. I really
don't like having a case like this where the pg_upgrade will fail from
something that we could have detected during the pre-flight check,
that's what it's for, after all.

Thanks,

Stephen