> the Query Graph Model (QGM) representation is quite abstract and hardcodes many properties, making it exceptionally difficult to understand. Its claimed extensibility is also questionable.

I don't know much about the context, but it was interesting to note that Materialize scrapped their QGM code last year: https://github.com/MaterializeInc/materialize/pull/17139

Also, a couple of interesting projects in the IR space:

- https://substrait.io/ is a cross-language serialization for Relational Algebra

- https://www.lingo-db.com/ is an MLIR-based (LLVM) query engine described extensively in this paper https://db.in.tum.de/~jungmair/papers/p2485-jungmair.pdf?lan...