Comment by mjb

(OP here). I don’t love leaking this kind of thing through the API. I think that, for most client/server shaped systems at least, we can offer guarantees like linearizability to all clients with few hard real-world trade-offs. That does require a very careful approach to designing the database, and especially to read scale-out (as you say) but it’s real and doable.

By pushing things like read-scale-out into the core database, and away from replicas and caches, we get to have stronger client and application guarantees with less architectural complexity. A great combination.