[I] Optimize infallible dictionary key casting in `try_new_from_builder` method [arrow-rs]

["albertlockett (via GitHub)" <gi...@apache.org>]

albertlockett opened a new issue, #7662:
URL: https://github.com/apache/arrow-rs/issues/7662

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   In https://github.com/apache/arrow-rs/pull/7611 we added a new method to the dictionary builders called `try_new_from_builder` that allows creating a new builder with the same values, but a different type for the dictionary keys.
   
   This method uses the `PrimitiveArray::try_unary` method to do the casting, but when casting infallible types (e.g. going from u8 -> u16 keys), it would probably be faster to use `PrimitiveArray::unary_mut`.
   
   We should improve the implementation of `try_new_from_builder` to use `unary_mut` where possible. It might also be good to have add benchmark for this method as part of this work, so we could measure if there really is a performance improvement.
   
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   Discussion https://github.com/apache/arrow-rs/pull/7611/files#r2143611512


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Re: [I] Optimize infallible dictionary key casting in `try_new_from_builder` method [arrow-rs]

["albertlockett (via GitHub)" <gi...@apache.org>]

albertlockett commented on issue #7662:
URL: https://github.com/apache/arrow-rs/issues/7662#issuecomment-2970983692

   Can assign this to me. I'll probably be able to find some time next couple weeks


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