I've always considered message-queues as a close cousin (if not sibling) of databases. Arguably performing the same function with different foci. Pub/sub focusi

I've always considered message-queues as a close cousin (if not sibling) of databases. Arguably performing the same function with different foci. Pub/sub focusing on the "oplog". DBMS focusing on "state". (Blockchain another "oplog" that ends up caring a lot about state eventually). It's no wonder you can use them interchangeably in many common base cases.