Introduction
When a query runs in ClickHouse®, the database does much more than simply read data and return results. Before execution begins, ClickHouse® parses the SQL statement, analyzes it, applies optimizations, and builds an execution plan that determines the most efficient way to process the query.
Understanding query execution plans is one of the most valuable skills for anyone working with ClickHouse®. They provide visibility into how queries are executed, helping you identify bottlenecks, validate optimization efforts, and troubleshoot performance issues.
In this article, we'll explore how ClickHouse® generates execution plans, the different EXPLAIN modes, and how to interpret them for better query optimization.
Why Query Execution Plans Matter
