MySQL and PostgreSQL are both well-known open-source relational databases. What happens if you want to move your application from MySQL to PostgreSQL?  Data migrations are always difficult; if you have a great deal of data, or you have used many of MySQL’s built-in functionality, then you may encounter problems. In this talk, Dimitri Fontaine describes  a real-life example of migrating a very large data set from MySQL to PostgreSQL. What was easy, and what was hard?  What does he recommend to others interested in doing so?