[aaroniba]

I think the article answers your question at the end of section 3.1:

> "This behavior may be surprising, but it is generally consistent with Datomic’s documentation. Nubank does not intend to alter this behavior, and we do not consider it a bug."

When you say, "situations leading to invariant violations" -- that sounds like some kind of bug in Datomic, which this is not. One just has to understand how datomic processes transactions, and code accordingly.

I am unaffiliated with Nubank, but in my experience using Datomic as a general-purpose database, I have not encountered a situation where this was a problem.

[aphyr]

This is good to hear! Nubank has also argued that in their extensive use of Datomic, this kind of issue doesn't really show up. They suggest custom transaction functions are infrequently written, not often composed, and don't usually perform the kind of precondition validation that would lead to this sort of mistake.

[aaroniba]

Yeah, I've used a transaction functions a few times but never had a case where two transaction functions within the same d/transaction ever interacted with each other. If I did encounter that case, I would probably just write one new transaction function to handle it.