You can pre-install a database on a Linux VPS at order time from the App dropdown: PostgreSQL, MariaDB (MySQL-compatible) or Redis (in-memory store). The server comes up with the database running and a ready-made app account.
appdb and a user called appuser with a random password, ready for your application.requirepass).The generated password is written to a text file in your home directory and in /root, for example oh-mariadb-credentials.txt, oh-postgresql-credentials.txt or oh-redis-credentials.txt.
For safety each database listens on the server itself, not the public internet. Reach it by forwarding its port over your SSH connection, then connecting to it as if it were local:
ssh -p PORT -L 3306:127.0.0.1:3306 USER@IPssh -p PORT -L 5432:127.0.0.1:5432 USER@IPssh -p PORT -L 6379:127.0.0.1:6379 USER@IPWith the tunnel open, point your database client at 127.0.0.1 on the same port. Apps running on the VPS itself just use localhost directly, no tunnel needed.
Straight answers.
MariaDB for MySQL-compatible apps like WordPress, PostgreSQL for apps that want Postgres, and Redis as a cache or queue alongside either. You can install more than one yourself afterwards.
In a text file in your home directory and in /root, for example oh-mariadb-credentials.txt. The app database and user are created for you.
The database listens on the server for security and only your SSH port is public by default. Open an SSH tunnel (commands above) and connect to 127.0.0.1, or expose the port deliberately if you know you need it.