Re: Database system identifier from SQL

Tom Lane wrote:
> Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> > Is there a way to query the database system identifier that
> > pg_controldata outputs from SQL?
>
> Don't think so. Do you have a use-case for providing a function to
> return that?

I'd like to find out whether two connections are really to the same
server.

This is in the context of an installation routine for a database
application which pulls the connection parameters for several databases
from a configuration file and creates various things there. It should,
however, only create roles once if the connection parameters point to
the same server (if the user only expects a small installation, say).

A workaround is to compare inet_server_addr() and inet_server_port(),
but that is not 100% safe because it doesn't cover Unix-domain sockets
using different paths.

--
Peter Eisentraut
http://developer.postgresql.org/~petere/