> The advice I've received upon asking this question in the past is clients first then server. We are currently running many 9.1 clients against some servers awaiting upgrade
> - the most ancient of which is 7.4. The only problem (annoyance, really) is that in interactive psql sessions, a few of the "\" commands don't work with the old servers
> due to differences in the system tables and similar internal changes between versions.
Thanks for that. It ties in with what I suspected, and what I've observed in informal tests.
> Also, if putting in the effort to upgrade, consider moving to 9.1 to get all the current feature and performance benefits.
I'll probably upgrade from 8.3 to 8.4 when I've got 8.3 running and tested. 8.4 is the latest version in the standard Debian Linux package
repository for the latest stable release. But at the moment, I'll just be happy to get 8.3 working, as there have been quite a few changes
between 8.1 and 8.3 which have required changes to the application.