Data Migration Strategies: Zero-Downtime Patterns, CDC, Dual Writes, and Proving Correctness
A practical guide to production data migration strategies—big-bang vs online migrations, expand/contract, dual writes, CDC, validation, cutover, and rollback. Includes runnable code, mermaid diagrams, and trade-offs commonly tested in system design interviews.
PostgreSQL
The world's most advanced open-source relational database, known for extensibility, standards compliance, and robust ACID transactions
MVCC (Multi-Version Concurrency Control)
How databases provide isolation without locking