Vantage resolves multiple grouping sets specifications by concatenating pairwise the individual elements of the sets. For information about grouping sets specifications, see the following:
When applied to specifications that contain multiple grouping specification elements, the resolution can be complicated.
For example, the following two GROUP BY clauses are semantically identical:
GROUP BY GROUPING SETS ((A,B), (C)), GROUPING SETS ((X,Y),()) GROUP BY GROUPING SETS ((A,B,X,Y),(A,B),(C,X,Y),(C))