viirya opened a new issue, #1690: URL: https://github.com/apache/arrow-rs/issues/1690
**Is your feature request related to a problem or challenge? Please describe what you are trying to do.** We keep a vector of `Field` and a `UnionMode` in `Union` datatype now. According to Arrow [spec](https://arrow.apache.org/docs/format/Columnar.html#union-layout), it only specifies the type ids are 8bit signed integers. So the type ids can be arbitrary integers only if they can be matched with children arrays' type ids. This is how [UnionType](https://github.com/apache/arrow/blob/d6e577899f1d0c62c1525ac0691026e6db89fd0d/cpp/src/arrow/type.cc#L620-L631) in C++ implementation works. Currently this crate assumes that the type ids of `Union` are monotonically increasing from 0 (i.e., 0, 1, 2...). When integrating with other implementations like C++, this assumption will cause error in receiving/sending UnionArray. **Describe the solution you'd like** We should keep type ids in `Union` datatype like C++ `UnionType`. The type ids are given when creating `Union` datatype. `UnionArray` related code should not assume the type ids are monotonically increasing from 0. **Describe alternatives you've considered** A clear and concise description of any alternative solutions or features you've considered. **Additional context** Add any other context or screenshots about the feature request here. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
