upgrading_postgresql.md

Install PostgreSQL 9.4

echo "deb http://apt.postgresql.org/pub/repos/apt/ precise-pgdg main" >
          /etc/apt/sources.list.d/pgdg.list
wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc 
          | sudo apt-key add -
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install postgresql-9.4 postgresql-contrib-9.4

Ensuring permission on pg_hba.conf

local   all             postgres                                peer

Shutdown service

sudo service postgresql stop

Execute pg_upgrade

sudo su postgres

/usr/lib/postgresql/9.4/bin/pg_upgrade -b /usr/lib/postgresql/9.1/bin/ \
          -B /usr/lib/postgresql/9.4/bin/ \
          -d /var/lib/postgresql/9.1/main \
          -D /var/lib/postgresql/9.4/main \
          -o ' -c config_file=/etc/postgresql/9.1/main/postgresql.conf' \
          -O ' -c config_file=/etc/postgresql/9.4/main/postgresql.conf'

Start service

sudo service postgresql start 9.4

Clean up

sudo apt-get remove postgresql-9.1