Pandas supports JOIN and GROUP BY operators so you are saying that there is a gap between Apache Arrow and other mature dataframe libraries? If there is a gap, is there no plan to fix it in the standard Arrow API?

I understand the case for a SQL-like DSL and an optimizer for distributed queries (in-memory column stores, not so much). I'm trying to understand the value add of Polars. I don't mean to come across as critical; perhaps DataFusion is a poor implementation and you are being too polite to say so.

I also think that there is a C++/Arrow vs Rust/Arrow decision that has to be made. I associate PyArrow with the C++/Arrow library. Is Polars' Eager API a superset of the PyArrow API with the addition of JOIN/GROUPBY/other operators?