ClickHouse Query Optimization Quick Start Check your query plan: This shows which parts of the index are used, how many partitions are read, and the aggregation strategy. When to Use - Write fast ClickHouse queries - Design table schemas - Analyze slow queries - Add data skipping indexes - Implement partitioning strategies - Use projections for multiple access patterns Core Principles 1. Primary Key Design The primary key defines sort order (not uniqueness). Order columns by low → high cardinality . Key principle : Queries must filter on primary key prefix to use index. 2. Data Skipping Index…