PostgreSQL notes

Discard and create a new PostgreSQL instance

https://stackoverflow.com/questions/2748607/how-to-thoroughly-purge-and-reinstall-postgresql-on-ubuntu

Passwords

https://chartio.com/resources/tutorials/how-to-set-the-default-user-password-in-postgresql/

PostgreSQL database passwords are separate from operating system user passwords. The password for each database user is stored in the pg_authid system catalog. Passwords can be managed with the SQL commands CREATE ROLE and ALTER ROLE, e.g., CREATE ROLE foo WITH LOGIN PASSWORD 'secret', or the psql command \password. If no password has been set up for a user, the stored password is null and password authentication will always fail for that user.

https://stackoverflow.com/questions/37861262/create-multiple-postgres-instances-on-same-machine