I would be genuinely curious what the OP other and folks here think of Mangle Datalog in this context. The go implementation is here: https://codeberg.org/TauCeti/mangle-go and the Rust implementation is here: https://codeberg.org/TauCeti/mangle-rs

The implementations are not high performance, but if you can fit everything in memory or you can organize your data and integrate it through external queries, you should get something workable for a lot of use cases.

I did not set out to replace SQL, and while I don't mind adoption, that is not why I am sharing it here. The open sourcing was motivated by making datalog more widely known. I did some research and found out that I needed a datalog implementation with particular characteristics, I for sure knew I didn't want to use SQL for what I needed.

There are structured types and recursion and being able to name predicates and compose queries... Mangle has some users and there is a few application that take advantage of the queries-as-logic-programming approach.

I think an insight one can draw in this discussion that a query language and the system (DBMS implementation) that it is part of can hardly be separated when it comes to the inevitable performance requirements one has.