Module functions 

Concrete implementations of aggregate functions

Structs

AvgFunction

AVG(column) - averages numeric values

CountFunction

COUNT(column) - counts non-null values

CountStarFunction

COUNT(*) - counts all rows including nulls

MaxFunction

MAX(column) - finds maximum value

MinFunction

MIN(column) - finds minimum value

StdDevFunction

STDDEV(column) - computes population standard deviation

SumFunction

SUM(column) - sums numeric values

VarianceFunction

VARIANCE(column) - computes population variance