ClickHouse Migration Deep Dive Overview Plan and execute ClickHouse schema migrations: column changes, engine migrations, ORDER BY modifications, and versioned migration runners. Prerequisites - ClickHouse admin access - Backup of production data (see ) - Test environment for validation Instructions Step 1: Understanding ClickHouse DDL ClickHouse ALTER operations are mutations — they run asynchronously and rewrite data parts in the background. This is fundamentally different from PostgreSQL/MySQL where ALTER is often instant or blocking. Step 2: Column Operations Step 3: Change ORDER BY (Requ…