The lambda architecture is more than one weird trick to enable querying massive data sets in real-time. It is a generalized blueprint for building data systems that fit your business requirements. It has been called a number of different names since the dawn of computer science: event sourcing, command query responsibility separation, materialized views. The main idea behind this pattern has stayed the same: keep your data processing functional. The goal of this talk is to show you how to leverage this fundamentally functional approach to data processing to build systems that scale, both to load and to business requirements.