[tomputer]

Where I work we've recently upgraded many PostgreSQL servers from 9.x/10.x/11.x to 14.x.

A very cool PostgreSQL feature is that, if you install a second instance on the same server, it will by default use a different path and port to run the second instance.

  root@example:~# pg_lsclusters
  Ver Cluster Port Status Owner    Data directory              Log file
  11  main    5432 online postgres /var/lib/postgresql/11/main /var/log/postgresql/postgresql-11-main.log
  14  main    5433 online postgres /var/lib/postgresql/14/main /var/log/postgresql/postgresql-14-main.log

Now you can dump and import databases on the second instance and test your applications with the new version. If it all works as expected, use pg_upgrade[1] to migrate everything to the new instance and switch the ports after the migration.

I have only done this migration process on Debian systems but in my experience it worked fantastic!

[1] https://www.postgresql.org/docs/current/pgupgrade.html