Describe the enhancement requested

The Arrow<->Substrait conversion currently only works with the types that are supported by both Arrow and Substrait. I would like to use Substrait expression conversion for filter pushdown (polars can convert to a pyarrow.compute expression, and datafusion can consume a substrait expression, and I would like to bridge the two).

This is currently blocked by the fact that polars uses large_string by default and pyarrow.compute expressions fail to serialize if they contain a large_string type.

Since I know that both the source and destination are arrow I should be able to use the arrow-specific types (substrait will consider them user defined types).

To simplify things, this request only asks for support for non-parameterized types. Arrow-specific parameterized types (e.g. decimal256, large_string, etc.) can come in a future request.

Component(s)

C++