Graph databases are exciting, but I&#x27;m far more interested in the potential of append-only stores. Rather than recording data at all, you store events (item added, item deleted, etc.).<p>This allows auditability and for you to look back at the state of the data at any time, but the largest benefit, in my opinion, is that it decouples data from its data structure. This allows you to treat data structures like &quot;caches&quot; that are efficiently structured for how they will be used. If you want, you don&#x27;t have to choose between relational databases or graph databases or anything else: you can play the same set of events into different structures and query the appropriately structured database for the kind of query you&#x27;re doing. It also allows you to implement security at the data storage level in a very simple and granular way: you can reject events based on predicates which update as themselves as they receive modifications to the permissions, and distribute filtered streams of data to users based on what events they are allowed to see. Overall, the power of this method is very large.