I'm curious about how the persistence primitives (OrderedTable, Table, etc) are implemented under the hood. Is it calling out to some other database service? Is it implemented in Unison itself? Seems like a really interesting composable set of primitives, together with the Database abstraction, but having a bit of a hard time wrapping my head around it!

Hey there! Apologies for not getting to you sooner. The `Table` is a storage primitive implemented on top of DynamoDB (it's a lower-level storage building block - as you've rightfully identified; these entities were made to be composable, so other storage types can be made with them). Our `OrderedTable` docs might be of interest to you: they talk about their own implementation a bit more (BTrees); and `OrderedTable` is one of our most ergonomic storage types: https://share.unison-lang.org/@unison/cloud/code/releases/23...

The Database abstraction helps scope and namespace (potentially many) tables. It is especially important in scoping transactions, since one of the things we wanted to support with our storage primitives is transactionality across multiple storage types.