This document discusses how RichRelevance solved real-time user segmentation using HBase. It describes how RichRelevance ingests user event data in real-time using Kafka and indexes it to various HBase tables. It then evaluates user segments defined in a UI by performing joins on the indexed HBase data in milliseconds. Key aspects included real-time data ingestion, optimized HBase key design, distributed data centers, and performance of 40K puts/sec and segment evaluation in milliseconds for millions of users.