Re: pg_upgrade using appname to lock out other users

Bruce Momjian wrote:
> Tom Lane wrote:
> > Bruce Momjian <bruce@momjian.us> writes:
> > > You might remember we added a postmaster/postgres -b switch to indicate
> > > binary upgrade mode.  The attached patch prevents any client without an
> > > application_name of 'binary-upgrade' from connecting to the cluster
> > > while it is binary upgrade mode.  This helps prevent unauthorized users
> > > from connecting during the upgrade.  This will not help for clusters
> > > that do not have the -b flag, e.g. pre-9.1.
> > 
> > > Does this seem useful?
> > 
> > No ... that seems like a kluge.  It's ugly and it's leaky.
> > 
> > What we really ought to be doing here is fixing things so that
> > pg_upgrade does not need to have a running postmaster in either
> > installation, but works with some variant of standalone mode.
> > That would actually be *safe* against concurrent connections,
> > rather than only sorta kinda maybe safe.
> 
> I keep replying to that suggestion by reminding people that pg_upgrade
> relies heavily on psql features, as does pg_dumpall, and recoding that
> in the backend will be error-prone.

Also, a standalone backend does not have libpq either so how do you get
values into application variables?  Parse the text output?  That seems
like a much larger kludge.

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

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