migration-strategies

Migration Strategies

When to use

• Planning zero-downtime schema changes or deployments
• Migrating from one framework/database to another
• Executing large-scale data migrations safely

Core principles

1. Never big bang — incremental migration with rollback at every step
2. Expand-contract for schema changes — add new, migrate, remove old
3. Batch data migrations — 1000 rows at a time, 50ms delay between batches
4. Test migration on production-size data — 100 rows works, 10M rows breaks differently
5. Rollback plan before migration plan — if you can't roll back, you can't ship

References available

• references/zero-downtime-migration.md — blue-green, canary, rolling with rollback procedures
• references/database-migration-patterns.md — expand-contract, schema versioning tools (Flyway, golang-migrate, Prisma), safe migration rules
• references/data-migration-patterns.md — dual-write between databases, batch ETL with cursor pagination, migration validation
• references/framework-migration.md — strangler fig pattern: CRA→Next.js, Express→Fastify, REST→GraphQL
• references/incremental-migration.md — step-by-step migration rules, rollback plans, shadow mode, monitoring during migration