Upgrading PostgreSQL

To upgrade a PostgreSQL installation start by dumping all the existing databases. You should do this before stopping the current database server
$ PGUSER=postgres /usr/bin/pg_dumpall > dump.sql
$ sudo /etc/init/d/postgresql stop
$ sudo mv /usr/local/pgsql /usr/local/pgsql.old

Build and install your new version. Be sure to create a PGDATA directory that is owned by the postgres user. Initialize the PGDATA directory with initdb
$ sudo mkdir /usr/local/pgsql/data
$ sudo chown postgres:postgres /usr/local/pgsql/data
$ sudo -u postgres /usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data

Once you have created your new database, start the new database server and populate the new database with the data you dumped from your old system:

$ sudo -u postgres /usr/local/pgsql/bin/postgres -D /usr/local/pgsql/data
$ sudo -u postgres /usr/local/pgsql/bin/psql -d postgres -f dump.sql