What is Lock?

A technique to prevent simultaneous access to data in a database to prevent inconsistent results. Modern databases all implement the granular row-level locking for performance reason. But some operations like altering the schema would still require table-level locking, which would block the normal online processing. That's the reason such operations are performed during non-business hours to reduce impact.

Safer and faster database change and version control for DBAs and Developers

Bytebase is an open source, web-based database schema change and version control tool for teams. It offers a web-based collaboration workspace to help DBAs and Developers manage the lifecycle of application database schemas.