Really curious what kind of problem requires 100.000s of DB servers, and what database system is actually capable of such massive horizontal scaling? Are you ab

Really curious what kind of problem requires 100.000s of DB servers, and what database system is actually capable of such massive horizontal scaling? Are you able to provide any specifics? I imagine that typically a single instance can serve at least 100-1000 concurrent users, meaning you have about 10 to 100.000.000 concurrent users on the system? Since you mentioned gaming I assume it's a massive multiplayer-game like Fortnite?