Re: Ability to listen on two unix sockets

I wrote:
> On the whole I prefer the solution you mention above: let's generalize
> the postmaster.pid format (and pg_ctl) so that we don't need to assume
> anything about port numbers matching up. The nearby discussion about
> allowing listen_addresses to specify port number would break this
> assumption anyway. If we just add two port numbers into postmaster.pid,
> one for the Unix socket and one for the TCP port, we could get rid of
> the problem entirely.

After further thought, I think that this approach would make it a good
idea to drop support for alternate port numbers from the present patch.
Let's just deal with alternate socket directories for now. There could
be a follow-on patch that adds support for nondefault port numbers in
both listen_addresses and unix_socket_directories, and fixes up the
postmaster.pid format to support that.

I will admit that part of my desire to do it this way is a narrow Fedora
rationale: in the Fedora package, we are going to want to back-patch the
alternate-directory feature into 9.2 (and maybe 9.1) so as to fix our
problems with systemd's PrivateTmp feature. The alternate-port-number
feature is not necessary for that, and leaving it out would make for a
significantly smaller back-patch. But in any case, it seems like adding
alternate-port-number support for Unix sockets and not doing it for TCP
ports at the same time is just weird. So I think it's a separate
feature and should be a separate patch.

regards, tom lane