FULL compatibility means backward and forward compatibility between which schemas?

• A. Backward Only
• B. Forward Only
• C. Backward and Forward Between X and X-1
• D. None

Answer: (C)

In schema evolution, compatibility checks ensure that different versions of a schema can still interoperate between producers and consumers. Full compatibility means both directions are supported between the current version and the immediately prior version. In other words, a system using the latest schema can read data written with the previous version, and systems using the previous version can read data written with the latest version. This mutual readability allows a smooth upgrade path where producers and consumers can run different versions during transition. Typically this is achieved by changes like adding optional fields with defaults or otherwise ensuring that newer fields don’t break older readers, and that older fields are still readable by newer readers.