Postgres

Postgres database have to be uprade as manually after a Debian upgrade.

1. First become the postgres user: su - postgres
2. Next, list all clusters: pg_lsclusters
3. See if any clusters have databases other than “postgres”, “template0”, and “template1”: psql --port NNNN --list (replace NNNN with the port number returned by the pg_lsclusters command, start clusters if necessary with: pg_ctlcluster VERSION main start)
4. When the most recent version has no other databases other than the defaults, you can drop it and then upgrade from the version that has a database. As root: systemctl stop postgresql@VERSION-main. As the postgres user: pg_dropcluster VERSION main
5. Upgrade the cluster with the databases you want to keep. Postgres will always upgrade to the most recent version: pg_upgradecluster VERSION main