[uberman]

I am eternally indebted to you for Pandas. Many thanks for that.

Are you talking about there being support for multiple language libraries like PyArrow or about there being multiple Apache projects that utilize Arrow like Parquet and Spark?

If not, I'm not following what sub-projects you are speaking about. As far as I know, Arrow is principally the Arrow Columnar Format and Arrow Flight with some other potentially interesting interfaces for compute kernels and CUDA devices.

Am I missing something?

[andygrove]

The Arrow project contains implementations in multiple languages. Some of these languages contain code that can evaluate expressions against Arrow data, or even execute full queries. The C++ and Rust implementations contain query capabilities, and the Java implementation contains the Gandiva library that can delegate to C++ via JNI to evalulate expressions, for example.