Re: pg_upgrade using appname to lock out other users

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.
        regards, tom lane