Ruuning two instances of Postgres on the same machine

Robert James <srobertjames@gmail.com> writes:

I'm currently running Postgres 8.2 on Windows XP. I would like to use some
8.4 features, but I don't want to migrate my 8.2. Is there any way to run
both instances together? Are there any problems with that?

What you need is
* different install directories
* different data directories
* different port numbers
I'm not sure how friendly the Windows installers are on the first point,
but otherwise it's not hard. All the developers have multiple versions
running on their machines all the time, so it's plenty well-tested.

Alternatively, is the procedure to move from 8.2 to 8.4 without data or
function loss documented anywhere?

Dump, reload, check for incompatibilities by testing your apps and/or
reading the release notes.

regards, tom lane