How to identify super-aggregate row in aggregation query result using the GROUPING() function?

GROUPING(exp) is a MySQL built-in function that returns 1 if the given exp is rolled up to all values in a super-aggregate row when the "GROUP BY exp WITH ROLLUP" clause is used. For example:

CREATE TABLE MyTable (name CHAR(8), size CHAR(8), quantity INTEGER);
INSERT INTO MyTable VALUES 
  ('ball', 'small',  10),
  ('ball', 'large',  20),
  ('ball',  NULL,     5),
  ('hoop', 'small',  15),
  ('hoop', 'large',   5),
  ('hoop',  NULL,     3);
 
SELECT SUM(quantity), name, GROUPING(name), size, GROUPING(size)
  FROM MyTable GROUP BY name, size WITH ROLLUP ORDER BY name, size; 
  -- +---------------+------+----------------+-------+----------------+
  -- | SUM(quantity) | name | GROUPING(name) | size  | GROUPING(size) |
  -- +---------------+------+----------------+-------+----------------+
  -- |            58 | NULL |              1 | NULL  |              1 |
  -- |             5 | ball |              0 | NULL  |              0 |
  -- |            35 | ball |              0 | NULL  |              1 |
  -- |            20 | ball |              0 | large |              0 |
  -- |            10 | ball |              0 | small |              0 |
  -- |             3 | hoop |              0 | NULL  |              0 |
  -- |            23 | hoop |              0 | NULL  |              1 |
  -- |             5 | hoop |              0 | large |              0 |
  -- |            15 | hoop |              0 | small |              0 |
  -- +---------------+------+----------------+-------+----------------+

Note that the SUM(quantity) value in the super-aggregate row is the super-sum of GROUP BY expressions being rolled up to all values.

Reference information of the GROUPING() function:

GROUPING(exp): int
  Returns 1, if the given exp is rolled up to all values 
  in a super-aggregate row; otherwise 0.

Arguments, return value and availability:
  exp: Required. The group by expression to be examined. 
  int: Return value. 1, if exp is rolled up.
  Available since MySQL 4.0.

⇒ JSON_ARRAYAGG() - Building JSON Array in Group

⇐ GROUP_CONCAT() - Concatenating Items in Group

⇑ MySQL Functions on Aggregation Groups

⇑⇑ MySQL Function References