`impl ArrowNativeType for i128`

[liukun4515]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

when I implement the comparison operation for decimal data type, I should support i128 for

arrow-rs/arrow/src/buffer/mutable.rs

Line 301 in 8b85aa0

pub fn extend_from_slice<T: ToByteSlice>(&mut self, items: &[T]) {

this function.

In the pr #779, The i128 has been added as ArrowNativeType, but this is change-api changes.

how should i continue this work?

@alamb
Can I cherry-pick part code of this #779 to release branch？

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[alamb]

I think back porting just the impl ArrowNativeType for i128 is a reasonable thing to do for the release branch.

The main reason it has the api-change label is that it adds a new enum variant for IntervalUnit

However, I expect that arrow 6.5.0 will be the last release created before the release of 7.0.0 (which I expect in 2 weeks time)

[liukun4515]

I think back porting just the impl ArrowNativeType for i128 is a reasonable thing to do for the release branch.

The main reason it has the api-change label is that it adds a new enum variant for IntervalUnit

However, I expect that arrow 6.5.0 will be the last release created before the release of 7.0.0 (which I expect in 2 weeks time)

Thanks for your feedback.

Now we use i128 to u8 slice to represent the decimal value, and we use the FixedsizeListBuilder to append decimal value. If the i128 is as the ArraowNativeType, maybe we can change it to the Int128Builder to append decimal value.

[alamb]

I believe this is now complete: https://sourcegraph.com/github.com/apache/arrow-rs/-/blob/arrow/src/datatypes/native.rs?L220-241&subtree=true