The GP is complaining about the need to run the upgrade cluster command, and reconfigure your server when you want to use a different version of postgres itself

The GP is complaining about the need to run the upgrade cluster command, and reconfigure your server when you want to use a different version of postgres itself. MySql does it transparently if you just open the database in the new server. Of course, lots of people also think it's a feature. But those aren't very vocal. Anyway, this is a main reason why people keep using old postgres versions, they have to think about upgrading, and they often don't.