Today I upgraded a production PostgreSQL 8.4 database to version 9.1. This was on a Debian server. ~ The first step is to make a full dump of your data. I personally like to store that dump somewhere safe before upgrading. As root:
su - postgres pg_dumpall > dump.sql exit cp ~postgres/dump.sql /root/ Now you can safely remove the postgresql-8.4 and install postgresql-9.1:
aptitude purge postgresql-8.4 aptitude install postgresql-9.1 Next check the postgresql configuration in /etc/postgresql/9.