When customers across the globe place orders on Amazon.com, those orders are processed through many different backend systems, including Herd, a workflow-orchestration engine developed by the Amazon eCommerce Foundation team. A mission-critical system used by more than 300 Amazon engineering teams, Herd executes over four billion workflows every day. Beginning in 2013, Herd’s workflow traffic was doubling year-over-year, and scaling its then dozens of horizontally-partitioned Oracle databases was becoming a nightmare, and this number kept increasing. To support Herd’s increasing scaling needs, and to provide a better customer experience, the Herd team had to re-architect its storage system and move its primary data storage from Oracle to Amazon DynamoDB. In this session, we discuss how we moved from Oracle to Amazon DynamoDB, walk through the biggest challenges we faced and how we overcame them, and share the lessons we learned along the way.