HAF was a recent addition to hivemind where you can store state on a node and have it decentralized to other nodes.
So instead of a dapp being a centralized database you can put the code on a hive node to maintain it’s state. This can be done with multiple nodes to increase the decentralization.
HiveSQL like functionality is a perfect use case. Although it would take a lot of space, would be impractical on all nodes.
RE: Let's Keep HiveSQL Free!