Median aggregate

The task of this code is to implement an aggregate function that calculates the median over an input set (typically values from a table). Documentation on how to create aggregates can be found in the official PostgreSQL documentation under User-defined Aggregates

A typical median query is:

SELECT median(temp) FROM conditions;

Compiling and installing

To compile and install the extension:

> make
> make install

Note, that depending on installation location, installing the extension might require super-user permissions.

Testing

Tests can be run with

> make installcheck