Druid: A Real-time Analytical Data Store - Discusses the Druid architecture in detail.
The RADStack: Open Source Lambda Architecture for Interactive Analytics - Discusses how Druid supports real-time and batch workflows.
Introduction to Druid - Discusses the motivations behind Druid and the architecture of the system.
Druid: Interactive Queries Meet Real-Time Data - Discusses how real-time ingestion in Druid works and use cases at Netflix.
Not Exactly! Fast Queries via Approximation Algorithms - Discusses how approximate algorithms work in Druid.
Real-time Analytics with Open Source Technologies - Discusses Lambda architectures with Druid.
Stories from the Trenches - The Challenges of Building an Analytics Stack - Discusses features that were added to scale Druid.
Building Interactive Applications at Scale - Discusses building applications on top of Druid.