As a developer I use the PostgreSQL database system to store data in. I am working on different projects, for different customers and running on different production machines. Some projects run version 8.4 and others 9.1. I expect more version differences.
What is the best way to avoid running into problems?
Install multiple versions in parallel, and use the version matching what the customer has for that customer's project.
http://apt.postgresql.org/ and http://yum.postgresql.org/ will help a lot.