Re: Help: Installing 9.6 breaks local connections to 9.2 on Centos 6.9

Ken Tanzer <ken(dot)tanzer(at)gmail(dot)com> writes:
> Hi. On a Centos 6.9 server (in the cloud with Rackspace), I'm wanting to
> install PGDG 9.6 alongside the already-running 9.2. After installing the
> 9.6 packages (and even before doing an initdb), I am no
> longer able to make a local connection to the 9.2 server. Instead I get
> the message:

> psql: could not connect to server: Connection refused
> Is the server running locally and accepting
> connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

Where is the 9.2 server making its socket ... /tmp ?

What it looks like is that you've started to use a libpq.so that is
following the Red Hat convention of putting the socket file in
/var/run/postgresql, rather than /tmp. I do not know exactly where
the PGDG packages stand on that theological issue, or whether they
changed between 9.2 and 9.6. But the first step would be to use
"ldd" to see which libpq your invoked psql is pulling in.

regards, tom lane