RATIO_TO_REPORT window function
Calculates the ratio of a value to the sum of the values in a window or partition. The ratio to report value is determined using the formula:
value of
ratio_expression
argument for the current row / sum of
ratio_expression
argument for the window or partition
The following dataset illustrates use of this formula:
Row# Value Calculation RATIO_TO_REPORT 1 2500 (2500)/(13900) 0.1798 2 2600 (2600)/(13900) 0.1870 3 2800 (2800)/(13900) 0.2014 4 2900 (2900)/(13900) 0.2086 5 3100 (3100)/(13900) 0.2230
The return value range is 0 to 1, inclusive. If ratio_expression is NULL, then the return value is NULL.
Syntax
RATIO_TO_REPORT ( ratio_expression ) OVER ( [ PARTITION BY partition_expression ] )
Arguments
 ratio_expression

An expression, such as a column name, that provides the value for which to determine the ratio. The expression must have either a numeric data type or be implicitly convertible to one.
You cannot use any other analytic function in ratio_expression.
 OVER

A clause that specifies the window partitioning. The OVER clause cannot contain a window ordering or window frame specification.
 PARTITION BY partition_expression

Optional. An expression that sets the range of records for each group in the OVER clause.
Return type
FLOAT8
Examples
The following example calculates the ratios of the sales quantities for each seller:
select sellerid, qty, ratio_to_report(qty) over (partition by sellerid) from winsales; sellerid qty ratio_to_report  2 20.12312341 0.5 2 20.08630000 0.5 4 10.12414400 0.2 4 40.23000000 0.8 1 30.37262000 0.6 1 10.64000000 0.21 1 10.00000000 0.2 3 10.03500000 0.13 3 15.14660000 0.2 3 30.54790000 0.4 3 20.74630000 0.27
For a description of the WINSALES table, see Sample table for window function examples.