On Mon, 2013-01-14 at 06:37 -0500, Peter Eisentraut wrote:
> Here is a patch to add an option -I/--idempotent to pg_ctl, the result
> of which is that pg_ctl doesn't error on start or stop if the server is
> already running or already stopped.
So apparently, pg_upgrade needs the existing behavior, so making the
idempotent option the only behavior won't work. Therefore, I think this
patch is still useful as originally presented. I've made one change
that pg_ctl won't print any messages if the -I option is used and the
server is already started/stopped.