Afaict their solution is "here's a prolog-ish query DSL that safely translates FP-ish code to joins".

That seems fine, but imo 1+Ns usually happen when you interleave business logic with database loads--like you have business logic that "really wants to be in a loop" b/c it's "not easily expressed in SQL" logic.

So, the author's ~3 lines of "a loop with zero business logic" is not that convincing, and seems like a premature claim to "solving 1+Ns"?

Like maybe if you can express truly generic business logic, and somehow that is translated into "evaled on the database-side" SQL?

(Disclaimer, I work on an ORM that does let you interleave business logic & database loads, and still avoids 1+Ns: https://joist-orm.io/goals/avoiding-n-plus-1s/)