A yearly tradition: we tag a handful of features as gifts from our engineering team.

ClickHouse is a leading platform for open-source columnar database technology and real-time analytics. With ClickHouse, developers can delve into documentation, case studies, and performance benchmarks to learn how to build highly scalable and performant analytical systems. It provides tips about ClickHouse's storage engine, query execution, and distributed architecture. Developers can gain insights into their data in real-time, enabling them to make informed decisions and extract  business insights.

ClickHouse

ClickHouse 25.12 introduces several performance optimizations and UX improvements. Numeric hints now display for all rows in multi-value results when space permits. The distinctJSONPaths function is 50x faster by using metadata instead of scanning JSON columns. DISTINCT queries on LowCardinality columns now operate on dictionary IDs rather than full values, improving performance up to 6x. SEMI JOIN queries benefit from filter pushdown optimization, reducing data scanned by 30% and improving query speed by similar margins.

Christmas gifts from the ClickHouse engineering team

Numeric hint when last column and enough horizontal space #

Optimize distinctJSONPaths aggregate function #

Optimize DISTINCT transform for LowCardinality Columns #

Use equivalent sets to push down filter for SEMI JOIN #