Apache DataFusion is an extensible query execution framework, written in Rust, that uses Apache Arrow as its in-memory format.
This crate is a submodule of DataFusion that provides structures and macros for documenting user defined functions.
Most projects should use the datafusion crate directly, which re-exports this module. If you are already using the datafusion crate, there is no reason to use this crate directly in your project as well.