Decimal Type Enhancements: Support for var* and stddev* Aggregate Functions

Why it matters

This feature enables users to perform variance and standard deviation calculations on Decimal columns, which was previously unsupported. It allows for more accurate and precise statistical analysis on decimal numeric data types.

How to use it

Users can directly apply the varPop, varSamp, stddevPop, and stddevSamp aggregate functions on columns with the Decimal type in their SQL queries as usual. For example:

SELECT varPop(decimal_column), stddevSamp(decimal_column) FROM table_name