In Avro schema evolution, removing or adding a field that has a default value is classified as which type?

In Avro schema evolution, removing or adding a field that has a default value is classified as which type?

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

Answer: (B)

In Avro schema evolution, full compatibility means both backward and forward compatibility hold: data written with the old schema can be read with the new schema, and data written with the new schema can be read with the old one. If you add or remove a field and give that field a default value, you preserve both directions. Adding a field with a default means old data (which doesn’t have that field) can be read by the new schema—the missing field is filled in with its default. Removing a field while keeping a sensible default for that field in the context of evolution allows older data to be read by the new schema and keeps newer data readable by older schemas, because differences in fields are either ignored or provided by defaults. This dual-direction compatibility is why the change is considered full compatibility.

In Avro schema evolution, full compatibility means both backward and forward compatibility hold: data written with the old schema can be read with the new schema, and data written with the new schema can be read with the old one. If you add or remove a field and give that field a default value, you preserve both directions.

Adding a field with a default means old data (which doesn’t have that field) can be read by the new schema—the missing field is filled in with its default. Removing a field while keeping a sensible default for that field in the context of evolution allows older data to be read by the new schema and keeps newer data readable by older schemas, because differences in fields are either ignored or provided by defaults. This dual-direction compatibility is why the change is considered full compatibility.