The STUN and TURN specifications allow for client authentication using usernames and passwords, and call this authentication via long-term credentials. In fact, TURN requires that clients authenticate by this means.
However, I would assume that almost all deployments run their STUN or TURN servers separately from their database server. For example, for a VOIP application that uses TURN servers, presumably all of the user data would be stored in a database, user account management might be primarily handled by a web server, while the clients would still need to be able to authenticate into a separate TURN server.
What's the best practice for the STUN/TURN server to access the usernames and passwords from the database to authenticate clients? If most deployments or your solution relies upon a particular STUN/TURN server implementation that supports specific features, any recommendations as to STUN/TURN servers would be appreciated as well.