Which schema evolution category applies when a field with a default value is added or removed in Avro?

Which schema evolution category applies when a field with a default value is added or removed in Avro?

• A. Forward
• B. Backward
• C. Partial
• D. Full

Answer: (D)

Adding or removing a field that has a default value keeps Avro schema evolution in both directions intact, so the change is considered full compatibility. When a field is added with a default, data written with the old schema can be read with the new schema because the new field can be filled in using its default value, satisfying backward compatibility. Conversely, data written with the new schema can be read by the old schema because the old reader doesn’t know about the new field and can ignore it, or treat its absence as acceptable, satisfying forward compatibility. The same idea applies when a field is removed: the remaining fields still map cleanly to the reader’s schema, and the presence or absence of the removed field doesn’t break decoding in either direction. Because the change works safely in both directions, it is classified as full compatibility.

Adding or removing a field that has a default value keeps Avro schema evolution in both directions intact, so the change is considered full compatibility.

When a field is added with a default, data written with the old schema can be read with the new schema because the new field can be filled in using its default value, satisfying backward compatibility. Conversely, data written with the new schema can be read by the old schema because the old reader doesn’t know about the new field and can ignore it, or treat its absence as acceptable, satisfying forward compatibility. The same idea applies when a field is removed: the remaining fields still map cleanly to the reader’s schema, and the presence or absence of the removed field doesn’t break decoding in either direction. Because the change works safely in both directions, it is classified as full compatibility.