Re: BUG #6706: pg_upgrade fails when plpgsql dropped/re-created

On Sat, Jun 30, 2012 at 02:37:47PM -0400, Tom Lane wrote:
> > However, surprisingly, a simple pg_dump/restore also does not preserve
> > the public schema permissions either.  :-(
>
> Right.  My point is that there is a whole lot of stuff that initdb
> creates but does not mark "pinned" in pg_depend, with the intention that
> users could drop it, and perhaps recreate similarly-named objects with
> different properties.  We have never had a very sane story for what
> would happen to such modified objects during dump/reload, and pg_upgrade
> is no better (or worse).  I don't think there's too much point in
> thinking about plpgsql alone without also worrying about
>
>     * system views (including the information schema)
>     * collations
>     * conversions
>     * text search dictionaries
>
> Now for a lot of this stuff, it's perhaps reasonable that a major
> version upgrade would restore the objects to standard state.  I'm
> thinking though that it's rather bad that we treat either the public
> schema or the plpgsql language that way.  In particular, an admin
> might have wished to remove or restrict those two objects for security
> reasons, in which case he'd not be very happy if pg_upgrade resurrected
> them or restored their default permissions.

Agreed  What surprised me is that pg_dumpall/restore brings them back to
their default state too, and I haven't seen any complaints.  (I would
complain.)

> BTW, I think your proposed fix doesn't work even without considering
> this angle --- it would prevent creation of the duplicate pg_extension
> row, but the binary-upgrade dump script is still going to try to create
> the extension's member objects.

Agreed.  The conditionally function call worked just fine, but all those
dependent helper functions made a simple solution impossible.

What I decided to do was just conditionally drop the extension, just
like we conditionally create the plpgsql extension in non-binary-upgrade
mode.  We could have just said drop/recreate of plpgsql was unsupported,
but it bothered me that we had different error cases for binary and
non-binary upgrades, which seemed odd.

Do we want to keep the FirstNormalObjectId on the condtional
drop/recreate?

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

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