api-guidelines/asynchronous-api-guidelines/kafka-asynchronous-guidelines/f_schema_data_evolution/backward-compatibility.md

Backward Compatibility

There are two variants here:

• BACKWARD - Consumers using a new version (X) of a schema can read data produced by the previous version (X - 1)
• BACKWARD_TRANSITIVE - Consumers using a new version (X) of a schema can read data produced by any previous version (X - 1, X - 2, ....)

The operations that preserve backward compatibility are:

• Deleting fields
  • Consumers with the newer version will just ignore the non-existing fields
• Adding optional fields (with default values)
  • Consumers will set the default value for the missing fields in their schema version