Database Migration Strategies

Database migrations are controlled schema and data evolution: adding columns, changing types, creating indices, backfilling data, and dropping old schema — all without downtime. The stakes are high: a bad migration can take production down, corrupt data, or cause prolonged recovery. Strategies span offline (downtime-required, simple rollback) to online (continuous traffic, complex tooling), frameworks (Liquibase, Flyway, Prisma Migrate), and deployment patterns (expand-contract, blue-green databases, shadow writes). Large-scale systems (100GB+ tables, billions of rows) require specialized tools (gh-ost, pt-online-schema-change, AWS DMS) and careful orchestration. Backend engineers who master migration safety command +$30–50k premium over those who cause production incidents. The salary impact is moderate (+$10–20k) but concentrated in senior/staff engineer roles where schema management defines infrastructure reliability. At scale (>$1B revenue), a single poorly-planned migration affecting 10k+ users = customer churn, SLA violation, and C-suite stress. Companies now hire "data platform" or "database reliability" engineers specifically to design safe migration frameworks. Stripe, Uber, Airbnb published case studies on zero-downtime migration patterns; mastering these patterns is expected for infrastructure-track engineers.