I wonder how hard it is for us to add new data types. In particular I need u128, u256, u512 as well as decimal512 & decimal1024 types.

the challenge is less at the delta-rs level and more at the arrow level, does arrow-rs already support them for parquet?

Probably can be defined as Fixed-size-binary extension types. Though not sure what the extension types support looks like for arrow-rs and parquet-rs

@rtyler Not yet. I just posted on the Arrow mailing list as well.

relevant: https://github.com/apache/arrow-rs/issues/2444