I didn't find the variant encoding spec[1] disallow empty keys, however, [2] might require a shredded key with naming. So I wonder whether empty keys are allowed?
Best, Xuwei Fu [1] https://github.com/apache/parquet-format/blob/master/VariantEncoding.md [2] https://github.com/apache/parquet-format/blob/master/VariantShredding.md#objects
