Alexander Copquin and Vlad Carballo, The Knot
8 out of 10 couples use TheKnot.com to help plan their wedding. A key part of planning involves selecting articles, photographs, and other resources and storing these in the user's Favorites. Recently we migrated major parts of our technology stack to open source technologies. As part of our migration strategy, we zeroed in on MongoDB, since it better suited our requirements for speed and data structure as well as eliminating the need for a caching layer. The transition required a period in which both our legacy and new API where working concurrently with data being persisted on both databases (SQL and Mongo) and all records were being synched with every request. We resourced to many strategies and applications to achieve this goal, including: Pentaho, AWS SQS and SNS, a queue messenger system and some proprietary ruby gems. In this session we will review our strategy and some of the lessons we learned about successfully migrating with zero downtime.