ClickHouse

ClickHouse is an open-source, column-oriented database management system built specifically for online analytical processing (OLAP) - queries that scan and aggregate large volumes of data, like counting events, computing averages, or building dashboards - rather than the row-by-row transactional workloads a general-purpose relational database is optimized for. Its columnar storage and vectorized query execution let it scan billions of rows and return aggregated results in real time.

It's commonly used as the query engine behind real-time analytics dashboards, product and business intelligence tools, observability and log analytics platforms, and large-scale event or clickstream analysis, and can ingest data continuously from sources like Apache Kafka (also in this catalog) for streaming analytics use cases.

ClickHouse is a fit for teams whose workload is fundamentally analytical - aggregating and reporting over large, mostly-append-only datasets - rather than transactional, where a row-oriented database like the PostgreSQL or MongoDB entries in this catalog would be a better fit.