John created FLINK-12304:
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             Summary: AvroInputFormat should support schema evolution
                 Key: FLINK-12304
                 URL: https://issues.apache.org/jira/browse/FLINK-12304
             Project: Flink
          Issue Type: Bug
          Components: Formats (JSON, Avro, Parquet, ORC, SequenceFile)
    Affects Versions: 1.8.0
            Reporter: John


>From the avro spec:

_A reader of Avro data, whether from an RPC or a file, can always parse that 
data because its schema is provided. But that schema may not be exactly the 
schema that was expected. For example, if the data was written with a different 
version of the software than it is read, then records may have had fields added 
or removed._

The AvroInputFormat should allow the application to supply a reader's schema to 
support cases where data was written with an old version of a schema and needs 
to be read with a newer version.  The reader's schema can have addition fields 
with defaults so that the old schema can be adapted to the new.  The underlying 
avro java library supports schema resolution, so adding support in 
AvroInputFormat should be straight forward.



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