It's not only possible, it's a core feature of slony. A large use case for
slony is upgrades which would otherwise require a dump / initdb / reload,
and in doing so require an unacceptably long outage. Just make sure your
slony versions match.

However for the upgrade you're talking about below, 7.4.16 to 7.4.18, you
don't need an initdb cycle, you can simply replace the binaries. I'd also
note that 7.4 is pretty long in the tooth at this point. You should consider
upgrading, although at this point I'd wait for 8.3 to come out and go in
that direction.

Andrew

On 11/6/07, Jan Matousek <honza at jyxo.com> wrote:
>
> Hi,
>
> I believe that the cross-version replication is possible.
> I have experience with 8.1 (master) and 8.2 (slave) replication, and
> it works fine.
>
> j.
>
> On Nov 6, 2007 1:38 PM, Geoffrey <lists at serioustechnology.com> wrote:
> > Is it absolutely necessary to have the same versions of Postgres on both
> > the master and slave?  Point is, we are currently running 7.4.16 on the
> > machines I plan to replicate, but thought I'd go with the lastest 7.4
> > version (18).  My ignorant assumption is that if you're going to have a
> > mis-match in versions, it's best to have the slave newer then the
> master.
> >
> > --
> > Until later, Geoffrey
> >
> > Those who would give up essential Liberty, to purchase a little
> > temporary Safety, deserve neither Liberty nor Safety.
> >   - Benjamin Franklin
> > _______________________________________________
> > Slony1-general mailing list
> > Slony1-general at lists.slony.info
> > http://lists.slony.info/mailman/listinfo/slony1-general
> >
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