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