Unsigned offset sizes

[JosiahParry]

I'm new to arrow & arrow-rs but had a question about the OffsetSizeTrait. I noticed that it is only implemented for i32 and i64. I find it interesting that it is not implemented for u32 or u64 as well. From my naive understanding, offsets would always be positive integers and not negative ones. Out of pure curiosity, what is the reason for not being able to use unsigned ints for an offset?

arrow-rs/arrow-array/src/array/list_array.rs

Line 40 in df69ef5

pub trait OffsetSizeTrait: ArrowNativeType + std::ops::AddAssign + Integer {

[tustvold]

The arrow format specification exclusively uses signed offsets - https://arrow.apache.org/docs/format/Columnar.html#list-layout

I believe this is due to some languages, such as Java, historically not having good support for unsigned integers

[JosiahParry]

Make enough sense! Thank you :)