[Server-devel] PostgreSQL mgmt on Fedora: pg_cluster-like tools?

[Ralf Corsepius]

On Sat, 2008-09-13 at 16:54 +1200, Martin Langhoff wrote:
> On Sat, Sep 13, 2008 at 12:07 AM, Tom Lane <tgl at redhat.com> wrote:
> >> Having been once the maintainer of the Pg compat layer in Moodle, I
> >> also have first-hand experience with this. When the casts removal was
> >> mentioned in pg-devel, who was there asking about backwards compat?
> >
> > If you need 100% backwards compatibility, you keep using 8.2
> 
> Perhaps wasn't clear - I wasn't complaining at all, just pointing out
> to Devrim that I am aware and active in tracking compat issues.
> 
> > Anyway, Devrim is quite right that mere installation of an RPM cannot
> > execute any sort of database conversion.  The functionality would need
> > to be invoked sometime else.  That doesn't mean it has to be manual
> > though.  Could we put it in the start script, invoked by something like
> > "service postgresql upgrade"?
Only if such conversion can be guaranteed not to fail.

In many cases this is not possible, because data-bases normally are
subject to different layers of authentication or might be networked.

> I completely agree.
> 
> >  Exactly what does a conversion look like
> > in Debian's packaging, anyway?
> 
>     * apt-get install postgresql-8.2
>     * pg_dropcluster –stop 8.2 main
>     * pg_upgradecluster -v 8.2 8.1 main /var/lib/postgresql/8.2/main
> 
> and if it works well, pg_dropcluster 8.1 main will delete the data dir
> of the old one.
I am not familiar with this particular case nor with postgres, but with
many mysql-based applications such approach is mostly certain to fail.

Ralf