GROUPING SETS as Dataset operator? Ordinals support?
I've been learning myself GROUPING SETS in Spark SQL and noticed it's
only supported in SQL mode. I _think_ it could be reasonably easy to
add support as Dataset operator. Has this been ever considered? Would
it be considered a part of Spark 2.2+?
I also noticed there's support for ordinals in groupBy and orderBy,
but doesn't seem supported in GROUPING SETS.
What do you think about adding the features to Spark SQL?