> I added a field with a default value to an Avro schema which is previously
> used for writing data. Is it possible to read the previous data using only
> new schema which has that new field at the end?
>
> I tried this scenario but unfortunately it throws EOFException while reading
> third field. Even though it has a default value and the previous fields is
> read successfully, I'm not able to de-serialize the record back without
> providing the writer schema I used previously.
>
> Schema schema = Schema.createRecord("test", null, "avro.test", false);
> schema.setFields(Lists.newArrayList( new Field("project",
> Schema.create(Type.STRING), null, null), new Field("city",
> Schema.createUnion(Lists.newArrayList(Schema.create(Type.NULL),
> Schema.create(Type.STRING))), null, NullNode.getInstance()) ));
> GenericData.Record record = new GenericRecordBuilder(schema) .set("project",
> "ff").build(); GenericDatumWriter w = new GenericDatumWriter(schema);
> ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
> BinaryEncoder encoder = EncoderFactory.get().binaryEncoder(outputStream,
> null); w.write(record, encoder); encoder.flush(); schema =
> Schema.createRecord("test", null, "avro.test", false);
> schema.setFields(Lists.newArrayList( new Field("project",
> Schema.create(Type.STRING), null, null), new Field("city",
> Schema.createUnion(Lists.newArrayList(Schema.create(Type.NULL),
> Schema.create(Type.STRING))), null, NullNode.getInstance()), new
> Field("newField", Schema.createUni
on(Lists.newArrayList(Schema.create(Type.NULL), Schema.create(Type.STRING))),
null, NullNode.getInstance()) )); DatumReader<GenericRecord> reader = new
GenericDatumReader<>(schema); Decoder decoder =
DecoderFactory.get().binaryDecoder(outputStream.toByteArray(), null);
GenericRecord result = reader.read(null, decoder);
>
