Apache Druid
Apache Druid is an open-source, real-time analytics database designed for high-performance queries on large-scale event-driven data. It combines features of data warehouses, timeseries databases, and search systems to enable fast aggregations and exploratory analytics on streaming and batch data. Druid is optimized for low-latency queries and high concurrency, making it ideal for interactive dashboards and operational analytics.
Developers should learn Apache Druid when building applications that require real-time analytics on massive datasets, such as monitoring systems, clickstream analysis, or IoT data processing. It is particularly useful for use cases involving time-based queries, high-cardinality dimensions, and sub-second query latencies, where traditional databases like PostgreSQL or Hadoop might struggle with performance. Druid's ability to ingest data from streaming sources like Kafka and batch sources like HDFS makes it a versatile choice for modern data architectures.