[rwhaling]

That was my immediate thought as well - CQRS doesn't fit well with the "everything should be deterministic" principle, unless they have a very different definition of CQRS than what is in common use.

In theory, it is possible to do "synchronous CQRS", where the update to your write-side is done in a single transaction with the update to the read-side, but that's not how I've ever done it in my (Scala/Postgres based) CQRS app experience.

[parsnips]

Compare and Swap is a command. E.g. Optimistic Concurrency.

[naasking]

Consistency and determinism are orthogonal. Just because updates are eventually consistent, doesn't mean they exhibit any sort of indeterminism.