Apache Druid vs Apache Pinot
Two Apache real-time OLAP databases built for fast queries on streaming data: Druid's master, query and data server roles with deep storage, a metadata store and ZooKeeper, against Pinot's controller, broker, server and minion design with upserts and star-tree indexes. Covers stream and batch ingestion, SQL and joins, cluster operations, and which suits internal dashboards versus user-facing analytics.

