CockroachDB, a distributed SQL database, offers a robust solution for performing online schema changes without the need for downtime, maintaining data consistency and application performance. Unlike traditional methods that require scheduled downtime, CockroachDB's schema change engine operates in the background, leveraging a consistent distributed schema cache that allows multiple schema versions to be used concurrently. This system, inspired by Google's F1 team, facilitates schema updates by using a staged process that sequentially grants and revokes capabilities, ensuring that changes such as adding or dropping indexes are executed smoothly across the entire cluster. By employing a lease mechanism for schema versions, CockroachDB accelerates the convergence to the latest schema version, allowing schema changes to be conducted during normal business hours, even during peak usage times. This approach not only eliminates the need for off-peak deployment but also aligns with modern operational practices, making it a popular choice for enterprises aiming for minimal disruption and maximum uptime.