Re: Re: [GENERAL] pg_upgrade from 9.0.7 to 9.1.3: duplicate key pg_authid_oid_index

On Sat, Jun 02, 2012 at 05:10:03PM -0400, Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > On Fri, Jun 01, 2012 at 09:52:59AM -0400, Tom Lane wrote:
> >> It seems that pg_upgrade needs a check to make sure that the bootstrap
> >> superuser is named the same in old and new clusters.
>
> > The attached patch adds checks to verify the the old/new servers have
> > the same install-user oid.
>
> That may or may not be a useful check to make, but it's got
> approximately nothing to do with what I was complaining about.
>
> In particular, supposing that the user has given you a username that
> isn't the bootstrap superuser in the new cluster, this patch is not
> going to stop the update script from failing.  Because the script is
> then going to try to replace the bootstrap superuser, and that is
> certainly going to give an error.
>
> I see the point of worrying about the install user as well as the
> bootstrap superuser, but wouldn't it be best to insist they be the same?
> Particularly in the new cluster, where if they aren't the same it means
> the user has manually created at least one role in the new cluster,
> which is likely to lead to OID conflicts or worse.
>
> Furthermore, if the bootstrap superusers aren't named the same, your
> patch fails to handle the original complaint.  In the case the
> OP mentioned, the old cluster had
>     OID 10: "ubuntu"
>     some user-defined OID: "postgres"
> and the new cluster had
>     OID 10: "postgres"
> If the user tells pg_upgrade to use username postgres, your check will
> not fail AFAICS, but nonetheless things are going to be messed up after
> the upgrade, because some objects and privileges that used to belong to
> the bootstrap superuser will now belong to a non-default superuser,
> whereas what used to belong to the non-default superuser will now belong
> to the bootstrap superuser.  That cannot be thought desirable.  For one
> reason, in the old installation the postgres role could have been
> dropped (possibly after dropping a few non-builtin objects) whereas the
> "ubuntu" role was pinned.  In the new installation, "postgres" is pinned
> and "ubuntu" won't be.
>
> I think the checks that are actually needed here are (1) bootstrap
> superusers are named the same, and (2) there are no roles other than the
> bootstrap superuser in the new cluster.

You are right that it is more complex than I stated, but given the
limited feedback I got on the pg_upgrade/plplython, I figured people
didn't want to hear the details.  Here they are:

There are three failure modes for pg_upgrade:

1.  check failure
2.  schema restore failure
3.  silent failure/corruption

Of course, the later items are worse than the earlier ones.  The
reporter got a "schema restore failure" while still following the
pg_upgrade instructions.  My initial patch changed that #2 error to a #1
error.  Tom is right that creating users in the new cluster (against
instructions), can still generate a #2 error if a new/old pg_authid.oid
match, and they are not the install user, but seeing that is something
that is against the instructions, I was going to leave that as a #2.

However, since Tom feels we should check that and make it a #1 failure,
I have added that test to the attached patch.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +