Teradata Database resolves multiple grouping sets specifications by concatenating pairwise the individual elements of the different sets. For information about grouping sets specifications, see:
This is trivial in the case of a simple grouping specification because it is a set containing only one element. However, when applied to more complicated specifications that contain multiple grouping specification elements, the resolution is more 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))