I have a four node setup consising of a master (node1), a slave 
(node2), and two other slaves that feed from node2, all of them 
running 8.1.x. I want to upgrade the farm to 8.4.3. Each Pg is 
installed using the package system of each OS.

I was thinking about compiling from source 8.4.3 in each node in a 
non-standard location, suscribing it as slave, waiting for it to 
synchronize, then upgrading to 8.4.3 via the package system, and 
renaming the source compiled data dir to where the package-installed 
Pg wants it. This would allow me to end with a Pg installed from 
package with minimum downtime. However, I'm unsure how the slony 
synchronization would react to that.

I'm thinking that other people might have faced the same scenario 
before (ie, wanting to upgrade without downtime *and* keeping the 
packages). Is there any document and/or experience of how to perform 
the upgrade?

Thanks in advance,

Fernando.