Yes, your production database is a text file really.

You can encode your facts in prolog style syntax and save it in a file and that's your database. You load it, and then ask your questions at the REPL.

If you wanted data that multiple people can change, you can actually connect prolog to an SQL database, then using query apply prolog rules and ask questions about your data.

I've been looking at this, too, after the recent surge in HN Prolog headlines.

You're probably looking for Datalog. The Wikipedia topic has a list of systems that support it: https://en.m.wikipedia.org/wiki/Datalog

Also, I found that AllegroGraph is a production graph database that supports Prolog queries... I don't think you load it with Prolog syntax, though--probably RDF triples instead.

LogicBlox more or less did that, though restricted to Datalog with various extensions. It's a commercial system though and not publicly available, except for online training material. See https://developer.logicblox.com/playground/ (since you probably don't know what to do, it's best to go to https://developer.logicblox.com/content/docs4/tutorial/repl/... )