Re: pg_upgrade: downgradebility

On Wed, 20 Sep 2006, Andrew Sullivan wrote:

> On Wed, Sep 20, 2006 at 12:54:14PM +0200, Zdenek Kotala wrote:
> > My first question is how important is downgrade for You and Your customers?
> >
> >
> > And second is how to verify that downgrade is possible?
>
> Well, one way to do it is to set up a Slony replica using the older
> version of the software. So, if you've upgraded to 8.1.x, you
> replicate to an old 8.0.x back end as well. If 8.1 doesn't work for
> you, you just MOVE everything back to the 8.0.x back end, and you're
> golden.

Well, I think that people who really want downgrade in such a tool are
those for which slony replication is just not an option. That is, data in
the range of hundreds of gigabytes. Using slony to upgrade is often not
practical either.

I wonder if pg_upgrade could be designed in such a way that upgrade is the
same as downgrade from a development point of view. That is, the tool can
change the system from one binary format to another.

Thanks,

Gavin