Patch for pg_upgrade to turn off autovacuum

Bruce Momjian wrote:
> Robert Haas wrote:
> > On Thu, Mar 31, 2011 at 12:11 PM, Bruce Momjian <bruce@momjian.us> wrote:
> > > Robert Haas wrote:
> > >> On Thu, Mar 31, 2011 at 11:32 AM, Heikki Linnakangas
> > >> <heikki.linnakangas@enterprisedb.com> wrote:
> > >> >> ?I think the maintenance
> > >> >> overhead of an invisible variable is too much.
> > >> >
> > >> > A simple GUC or command-line switch isn't much code.
> > >>
> > >> I like the idea of a command-line switch.
> > >
> > > If you want to do that you should gereralize it as --binary-upgrade in
> > > case we have other needs for it.
> > 
> > Yeah.  Or we could do a binary_upgrade GUC which has the effect of
> > forcibly suppressing autovacuum, and maybe other things later.  I
> > think that's a lot less hazardous than fiddling with the autovacuum
> > GUC.
> 
> I like the idea of a command-line flag because it forces everything to
> be affected, and cannot be turned on and off in sessions --- if you are
> doing a binary upgrade, locked-down is good. :-)

The attached patch adds a new postmaster/postgres binary upgrade mode
(-b) which disables autovacuum, allows only super-user connections, and
prevents pg_upgrade_support oid assignment when not in upgrade mode. 
It also modifies pg_upgrade to use this new mode rather than play with
trying to stop autovacuum.

This does fix a very rare bug that could happen if
autovacuum_freeze_max_age were set to maximum by the user.

I think this should be applied to PG 9.1.

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

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