You need to rename a column in a large table that a service is actively using under load, and do it with zero downtime. How would you run the migration and the deployment?
~4 min by voice
How to approach it
The interviewer checks whether the candidate understands that the database schema and the code are not deployed atomically: during a rolling deploy the old and new versions live side by side. You need to show how to split the change into backward-compatible steps (expand/contract), avoid locking the table, and keep a rollback option at every stage.
The interviewer will ask this question and listen. Think out loud and ask for a hint if you need one. When you're done, pause or tap “That's my answer”. In about a minute, your score and the points you covered show up here.