No, it hasn't. It is possible to layer an optimistic concurrency model for session transactions on top of our protocol, but the database standard library is sufficiently full-feature that it's easy to express most application logic as a pure function over the current state of the database.

Most read/modify/write cycles end up being essentially that, but with the added confusion of local application threading and standard library. We eliminate that, but preserve the general ability to express a complex query in application code (which also increases application concurrency since the database executes transactions with maximum parallelism.)

Transactions do not have to be pre-registered as stored procedures.