There are many blogs explaining how HyperLogLog works. We even have a few open-source implementations of HyperLogLog (in Java, Python, C++). Documentation on writing UDAF for Apache Hive is readily ...

Community Tutorial 06: Java-Hive Integration - Salary Delta Analysis and Visualization Using Hive, Java and JFreeChart This tutorial is from the Community part of tutorial for Hortonworks Sandbox - a ...