************************************ Aggregation Functions ************************************ .. function:: avg (expression) Returns the average of all input values. :param expression: :type expression: int | float :rtype: float8 .. function:: corr (expression1, expression2) Returns the coefficient of correlation between a set of number pairs. :param expression1: :param expression2: :type expression1: int | float :type expression2: int | float :rtype: float8 .. function:: count() Returns the number of input rows. :rtype: int8 .. function:: last_value(expression) Returns the last value of expression. :param expression: :type expression: int | float | date | time | timestamp | text :rtype: same as parameter data type .. function:: max(expression) Returns the maximum value of expression. :param expression: :type expression: int | float | date | time | timestamp | text :rtype: same as parameter data type .. function:: min(expression) Returns the minimum value of expression. :param expression: :type expression: int | float | date | time | timestamp | text :rtype: same as parameter data type .. function:: stddev_pop(expression) Returns the population standard deviation of a set of numbers. :param expression: :type expression: int | float :rtype: float8 .. function:: stddev_samp(expression) Returns the sample standard deviation of a set of numbers. :param expression: :type expression: int | float :rtype: float8 .. function:: sum(expression) Returns the sum of a set of numbers. :param expression: :type expression: int | float :rtype: same as parameter data type .. function:: var_pop(expression) Returns the variance of a set of numbers. :param expression: :type expression: int | float :rtype: float8 .. function:: var_samp(expression) Returns the unbiased sample variance of a set of numbers. :param expression: :type expression: int | float :rtype: float8