Hi everyone, Recently I took a stab at implementing reading UknownType <https://github.com/apache/iceberg/pull/13445> in the Java implementation. I thought it would make sense to add this to the reference implementation first. However, I ran into a limitation with the current definition in the spec:
Must be optional with null defaults; not stored in data files One obvious limitation is that it cannot be the key of a MapType, as it has to be not-null. It can't be stored either as the value of a MapType since there is no easy way to store just the key without doing awkward things, such as writing just the keys as a list. My initial idea was to disallow the use of UnknownType as the element in ListType and not allow the UnknownType as either a Key or Value of a MapType. Any thoughts or concerns? Kind regards from Belgium, Fokko
