Categories:

Aggregate Functions (General) , Window Functions

PERCENTILE_DISC

Returns a percentile value based on a discrete distribution of the input column (specified in order_by_expr). The returned value is that whose row has the smallest CUME_DIST value that is greater than or equal to the given percentile. NULL values are ignored in the calculation.

See also:

PERCENTILE_CONT

Syntax

Aggregate function

PERCENTILE_DISC( <percentile> ) WITHIN GROUP (ORDER BY <order_by_expr> )

Window function

PERCENTILE_DISC( <percentile> ) WITHIN GROUP (ORDER BY <order_by_expr> ) OVER ( [ PARTITION BY <expr3> ] )

Arguments

percentile

The percentile of the value that you want to find. The percentile must be a constant between 0.0 and 1.0. For example, if you want to find the value at the 90th percentile, specify 0.9.

order_by_expr

The expression (typically a column name) by which to order the values. For example, if you want to want to find the student whose math SAT score is at the 90th percentile, you’ll specify the column containing the math SAT score.

Note that this is also implicitly the column from which the returned value is chosen; e.g. if you order by math SAT scores, then the result you’ll get is one of the math SAT scores. You can’t order by one column and get a percentile value for a different column.

expr3

This is the optional expression used to group rows into partitions.

Returns

Returns the value that is at the specified percentile.

Usage Notes

  • The percentile argument to the function must be a constant.

  • DISTINCT is not supported for this function.

  • The function PERCENTILE_CONT interpolates between the two closest values, while the function PERCENTILE_DISC chooses the closest value rather than interpolating.

  • When used as a window function:

    • This function does not support:

      • ORDER BY sub-clause in the OVER() clause.

      • Window frames.

Examples

The following example shows the values at the 25th percentile (0.25) within various groups:

Create and populate a table with values:

create or replace table aggr(k int, v decimal(10,2));
insert into aggr (k, v) values
    (0,  0),
    (0, 10),
    (0, 20),
    (0, 30),
    (0, 40),
    (1, 10),
    (1, 20),
    (2, 10),
    (2, 20),
    (2, 25),
    (2, 30),
    (3, 60),
    (4, NULL);

Run a query and show the output:

select k, percentile_disc(0.25) within group (order by v) 
  from aggr 
  group by k
  order by k;
+---+-------------------------------------------------+
| K | PERCENTILE_DISC(0.25) WITHIN GROUP (ORDER BY V) |
|---+-------------------------------------------------|
| 0 |                                           10.00 |
| 1 |                                           10.00 |
| 2 |                                           10.00 |
| 3 |                                           60.00 |
| 4 |                                            NULL |
+---+-------------------------------------------------+