At Facebook, we open sourced MyRocks -- Flash optimized, space and write efficient MySQL database engine. We are in the process of migrating our main MySQL databases -- storing Facebook social graphs, massively sharded, low latency and automated services -- from InnoDB to MyRocks. We have been very successful so far and have reduced database size by half. Compared to deploying new software into new or non-critical services, replacing existing stable database engines running on very critical services is much harder. You need to pay attention to lots of things, like how to migrate without stopping or slowing down services, how to migrate within reasonable amount of time, and how to continuously verify not to corrupt any data. In this session, the speaker will talk about MyRocks production deployment story. You will learn about the followings. - Overview of MySQL at Facebook - What is RocksDB and MyRocks, and why we decided to create yet another database engine - How we prepared, executed and monitored InnoDB to MyRocks migration - Lessons learned from the migration.