What to do with a PAAS-pg server

Hi,

we have a supplier (via our client) who has an self build PAAS-version
of postgresql. Ok, you would say, that's fine. But, there is always an
but, we think the settings are not quite ok. We really want to know how
much memory etc there is on that server. So we can recommend the
recommended settings. Is there a way to get those information on the
server itself from psql?

regards,

Alexander Al