v.25.9Experimental Feature

Join reordering now uses statistics

Join reordering now uses statistics. The feature can be enabled by setting allow_statistics_optimize = 1 and query_plan_optimize_join_order_limit = 10. #86822 (Han Fei).
Join reordering in ClickHouse query planning now leverages table statistics for improved optimization.

Why it matters

This feature enhances the efficiency of join order selection by using statistics, leading to potentially better query execution plans and performance improvements, especially for complex multi-join queries.

How to use it

Enable the feature by setting the configuration parameters allow_statistics_optimize = 1 and query_plan_optimize_join_order_limit = 10 in your ClickHouse server or session settings.