Upgrade to PostgreSQL 12

Introduction

Upgrading to PostgreSQL 12 is a simple procedure requiring minimum downtime.

The process consists of 3 steps:

• Installing PostgreSQL 12 without a new cluster
• Migrating the database
• Optionally dropping the old cluster

Installing PostgreSQL 12

Install PostgreSQL 12 and drop the default cluster:

apt update
apt install --yes postgresql-12
pg_dropcluster 12 main --stop

Upgrade the existing cluster to PostgreSQL 12

For example if you currently use PostgreSQL 11:

pg_upgradecluster 11 main

# Success. Please check that the upgraded cluster works. If it does,
# you can remove the old cluster with
#     pg_dropcluster 11 main

# Ver Cluster Port Status Owner    Data directory              Log file
# 11  main    5433 down   postgres /var/lib/postgresql/11/main /var/log/postgresql/postgresql-11-main.log
# Ver Cluster Port Status Owner    Data directory              Log file
# 12  main    5432 online postgres /var/lib/postgresql/12/main /var/log/postgresql/postgresql-12-main.log

Optionally drop the old cluster and uninstall the old version of PostgreSQL

Once you have established that your upgraded database is working as expected you can drop the old cluster then uninstall the old version.

For example if you were previously using PostgreSQL 11:

# Drop the cluster
pg_dropcluster 11 main

# Uninstall the old packages
sudo apt purge --yes postgresql-11 postgresql-client-11