Migrating Yelp Reservations from PostgreSQL to MySQL

This blog post details Yelp's in-place migration of their Yelp Reservations service database from PostgreSQL to MySQL. The migration, necessitated by maintenance and expertise limitations with PostgreSQL, involved significant code refactoring to address unsupported features and ensure data consistency. A gradual rollout strategy, employing multi-DB support and careful synchronisation, was implemented to minimise disruption. The process revealed several unexpected challenges, including issues with auto-incrementing keys and ProxySQL memory usage, highlighting the complexities of such…