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 clickhouse-prod-checklist)
• 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