A Practical Guide to Database Migration: From Legacy Systems to Modern Infrastructure

Migrating databases is one of those projects that looks simple on paper and reveals all its complexity only when you're in the middle of it. Here's a guide based on common patterns and pitfalls. When to Migrate Not every legacy database needs migration. Signs you should consider moving: Vendor is sunsetting your version Licensing costs are unsustainable You're hitting scaling limits that can't be solved vertically Your team can't hire for the specific technology anymore Migration Strategies Lift and Shift Move the database to managed infrastructure with minimal changes. Example: self-hosted PostgreSQL 11 → RDS PostgreSQL 15. Pros: Fast, low risk Cons: You're still on the same old architecture Re-platform Make moderate changes to take advantage of cloud features. Example: self-hosted MySQL → Amazon Aurora MySQL. Pros: Better performance without full rewrite Cons: Some code changes required Refactor / Re-architect Full rewrite. Move from legacy relational to modern distributed database.