Use case
Have ability to distinguish rows being produced by GROUP BY and ROLLUP / CUBE.

Describe the solution you'd like
Just like in oracle or other databases.
https://oracle-base.com/articles/misc/rollup-cube-grouping-functions-and-grouping-sets

Describe alternatives you've considered
Using nulls as suggested in #8091 (comment), but it's not always applicable.

Additional context
#8091