Migrating a database from InnoDB to MyRocks

What this post added

This post details the successful migration of Facebook's UDB tier from the InnoDB storage engine to MyRocks, a RocksDB-based engine for MySQL. The migration achieved a 50% reduction in storage usage by addressing the space-bound nature of InnoDB on flash storage. Key technical contributions include the development and application of comprehensive data consistency verification tools (primary/secondary key checks, cross-instance checks, shadow query replay), a phased migration strategy leveraging MyRocks' ability to replicate from InnoDB and vice-versa, and addressing technical challenges like buffered I/O and slow file deletion on flash storage. The post also highlights lessons learned regarding migration time estimation, understanding service usage for feature prioritization, starting small with new software deployments, and the benefits of open-source collaboration.