Simon Willison’s Weblog

Over the years, across multiple deployments, DynamoDB has learned that it’s not just the end state and the start state that matter; there could be times when the newly deployed software doesn’t work and needs a rollback. The rolled-back state might be different from the initial state of the software. The rollback procedure is often missed in testing and can lead to customer impact. DynamoDB runs a suite of upgrade and downgrade tests at a component level before every deployment. Then, the software is rolled back on purpose and tested by running functional tests. DynamoDB has found this process valuable for catching issues that otherwise would make it hard to rollback if needed.

— Amazon DynamoDB: A Scalable, Predictably Performant, and Fully Managed NoSQL Database Service