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Aggregate functions (General)

GROUPING_ID

Describes which of a list of expressions are grouped in a row produced by a GROUP BY query.

Alias for GROUPING.

Syntax

GROUPING_ID( <expr1> [ , <expr2> , ... ] )

Usage notes

GROUPING_ID is not an aggregate function, but rather a utility function that can be used alongside aggregation, to determine the level of aggregation a row was generated for:

  • GROUPING_ID(expr) returns 0 for a row that is grouped on expr, and 1 for a row that is not grouped on expr.

  • GROUPING_ID(expr1, expr2 , … , exprN) returns the integer representation of a bit-vector containing GROUPING_ID(expr1) , GROUPING_ID(expr2) , … , GROUPING_ID(exprN).

Examples

The examples use the following table and data:

CREATE OR REPLACE TABLE aggr2(col_x int, col_y int, col_z int);
INSERT INTO aggr2 VALUES (1, 2, 1), 
                         (1, 2, 3);
INSERT INTO aggr2 VALUES (2, 1, 10), 
                         (2, 2, 11), 
                         (2, 2, 3);

This example groups on col_x. Calling GROUPING_ID(col_x) returns 0, indicating that col_x is indeed one of the grouping columns.

SELECT col_x, sum(col_z), GROUPING_ID(col_x)
    FROM aggr2 
    GROUP BY col_x
    ORDER BY col_x;
+-------+------------+--------------------+
| COL_X | SUM(COL_Z) | GROUPING_ID(COL_X) |
|-------+------------+--------------------|
|     1 |          4 |                  0 |
|     2 |         24 |                  0 |
+-------+------------+--------------------+

This query groups by sets:

SELECT col_x, col_y, sum(col_z), 
       GROUPING_ID(col_x), 
       GROUPING_ID(col_y), 
       GROUPING_ID(col_x, col_y)
    FROM aggr2 
    GROUP BY GROUPING SETS ((col_x), (col_y), ())
    ORDER BY col_x ASC, col_y DESC;
+-------+-------+------------+--------------------+--------------------+---------------------------+
| COL_X | COL_Y | SUM(COL_Z) | GROUPING_ID(COL_X) | GROUPING_ID(COL_Y) | GROUPING_ID(COL_X, COL_Y) |
|-------+-------+------------+--------------------+--------------------+---------------------------|
|     1 |  NULL |          4 |                  0 |                  1 |                         1 |
|     2 |  NULL |         24 |                  0 |                  1 |                         1 |
|  NULL |  NULL |         28 |                  1 |                  1 |                         3 |
|  NULL |     2 |         18 |                  1 |                  0 |                         2 |
|  NULL |     1 |         10 |                  1 |                  0 |                         2 |
+-------+-------+------------+--------------------+--------------------+---------------------------+