PostgreSQL is a database used in various sub projects at open food facts.
Docker compose based projects like robotoff or openfoodfacts-query use their own instance of the database in docker containers.
If data in the database is the primary source, it is advised to have a backup volume (typically a nfs or zfs volume) to backup the database regularly with a pg_dump. It might be more reliable and manageable than to only rely on the filesystem snapshot made by Proxmox/ZFS.
For Product Opener instances we only use the postgreSQL for minions tasks.
It is in a Proxmox container, right now there is no customization. Backup and is not a thing as it is transient data.
TODO: at least have data in a ZFS volume (through a bind mount) ?