Re: multiple instances on one box?

On Mon, 3 Jun 2002 15:18:26 -0400 (EDT)
Andrew Perrin <clists(at)perrin(dot)socsci(dot)unc(dot)edu> wrote:

> > To elaborate, I want to start one Postgres listening on say 7000 for
> > $DATA=/opt/pgdata1 and another Postgres listening on say 7100 for
> > $DATA=/opt/pgdata2.
>
> What's the reason for doing this? Just use separate databases -- if
> necessary, with different users given permissions on each -- in the same
> postmaster instance.

Easy mobility of databases from one computer to another.

Theory says different databases within one instance and different
instances have the same expressive power. Therefore, theory would dictate,
moving a database between instances is as easy as moving instances between
computers.

Reality is that moving a database from one instance to another is more
difficult than moving an instance from one computer to another. The former
requires specialised tools that are complicated and error-prone. The
latter requires generic tools (you know, like 'scp') that are simple.

In saying that, I make an assumption: that Postgres is similar to Sybase
or Oracle and that once a database achieves a certain complexity, the
tools (that allow database migration on small example databases) don't
scale to multi-gigabyte multi-hundred relations databases.

YMMV.

I'm still interested in knowing if running multiple instances on a single
computer is possible and how to do it. :)

--
Tim Ellis
DBA, Gamet