Apache Druid (part 1): A Scalable Timeseries OLAP Database System

Online analytical processing (OLAP) systems are commonly used in many Business Intelligence, Analytics and Data Science applications. According to Wikipedia, “OLAP is an approach to answer multi-dimensional analytical queries swiftly in computing”. Compared to traditional relational database systems, the main difference is that the data in an OLAP system is being stored in a pre-aggregated and multi-dimensional form. The main benefit of storing data in such form, is that it is optimized for ad-hoc complex aggregations. »