Ship database changes safely with expand and contract

Introduction

Walks through renaming a column with zero downtime, including the dual-write window and how to prove both paths agree before you drop the old one.

Small things that compounded

Looking back over Pattern work, the wins were unglamorous: a naming fix, a deleted config, a checklist nobody has had to edit since.

What made them stick

• They were owned by one person, not a committee.
• They shipped with a way to notice when they stopped working.
• They removed a decision instead of documenting one.

Steal this

Pick the irritation you have mentioned three times this month. That is your next project — it has already proven its staying power.

Closing

Big rewrites make better stories; small compounding makes better systems.