Re: Connect without specifying a database?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Sam Mason <sam(at)samason(dot)me(dot)uk>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Connect without specifying a database?
Date: 2009-04-11 18:25:05
Message-ID: 3121.1239474305@sss.pgh.pa.us
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Sam Mason <sam(at)samason(dot)me(dot)uk> writes:
> As others have said; the design of PG is such that it's built to assume
> you're always connected to exactly one database. I'd guess this is an
> artifact from a long time ago when PG didn't have multiple databases.

It's possible that that was true way back in Berkeley prehistory; there
is no one around the project now that would remember (unless maybe Elein
does). But the key points here are that critical catalogs like pg_class
and pg_proc are per-database, which is a good thing for quite a number
of reasons, and PG is sufficiently catalog-driven that it's literally
impossible for the engine to do anything useful without having a set of
those catalogs available. (Offhand, the only user-visible functionality
I can think of that isn't catalog-dependent is the GUC parameters, ie
SET/SHOW; and even within that there are some individual parameters
that can't meaningfully be set without catalog access.)

regards, tom lane

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