> > I'm awaiting community feedback about the approach to implementing > extension types, whether the approach that I've used (using the > following keys in custom_metadata [1]) is the one that we want to use > longer-term. This certainly seems like a good time to have that > discussion. If there is consensus then we can document it formally in > the specification documents, and we probably will want to hold a vote > to ensure that we are in agreement. >
Please let me know if this is best on a separate thread. I think I would feel more comfortable finalizing this if we had a few more examples exercising the functionality. Inet, seems like a complicated enough use-case for modeling which would make it a good use-case (It seems like it might involve a struct/union?). I also presume we will need a Java implementation, before we finalize anything? A small amount of bikeshedding on key names: We should probably take a namespace reservation approach for custom metadata in Schema.fbs [1]. In this regard I have a small preference for something reserving all metadata with something like "ARROW:<reserved_arrow_key>" or "ARROW." (not an underscore, and I'm open to different capitalization.) This seems to be a similar approach to how avro reserves metadata keys [2]. [1] https://github.com/apache/arrow/blob/b8aeb79e94a5a507aeec55d0b6c6bf5d7f0100b2/format/Schema.fbs#L264 [2] https://avro.apache.org/docs/1.8.1/spec.html
