Data migrations are an essential part of managing databases, often required for version upgrades, sharding, or moving to a new platform. However, they can be challenging and risky, with potential downtime, data loss, and compatibility issues. PlanetScale has developed a process that enables zero-downtime migrations at petabyte scale. This involves taking consistent non-locking snapshots of the data, replicating changes throughout the migration process, verifying the new system, cutting over application traffic to the new system, and decommissioning the old system when ready. PlanetScale's approach ensures that the entire migration can be done without any downtime or impact on live production systems.