Hi,
I think your usage of default for field "agentType" is invalid here.
When generating code from invalid schema, it tends to fail:
[INFO]
> [INFO] --- avro-maven-plugin:1.7.6-cdh5.4.4:schema (default) @ test-app ---
> [WARNING] Avro: Invalid default for field agentType: "APP_AGENT" not a
> ["null","string"]
Try:
{
> "namespace": "xx.xxxx.xxxxx.xxxxx",
> "type": "record",
> "name": "MyPayLoad",
> "fields": [
> {"name": "filed1", "type": "string"},
> {"name": "filed2", "type": "long"},
> {"name": "filed3", "type": "boolean"},
> {
> "name" : "metrics",
> "type":
> {
> "type" : "array",
> "items":
> {
> "name": "MyRecord",
> "type": "record",
> "fields" :
> [
> {"name": "min", "type": "long"},
> {"name": "max", "type": "long"},
> {"name": "sum", "type": "long"},
> {"name": "count", "type": "long"}
> ]
> }
> }
> },
> {"name": "agentType", "type": ["null", "string"], "default": null}
> ]
> }
On Mon, Feb 1, 2016 at 8:31 PM, Raghvendra Singh <rsi...@appdynamics.com>
wrote:
>
>
> down votefavorite
> <http://stackoverflow.com/questions/34733604/avro-schema-doesnt-honor-backward-compatibilty#>
>
> I have this avro schema
>
> {
> "namespace": "xx.xxxx.xxxxx.xxxxx",
> "type": "record",
> "name": "MyPayLoad",
> "fields": [
> {"name": "filed1", "type": "string"},
> {"name": "filed2", "type": "long"},
> {"name": "filed3", "type": "boolean"},
> {
> "name" : "metrics",
> "type":
> {
> "type" : "array",
> "items":
> {
> "name": "MyRecord",
> "type": "record",
> "fields" :
> [
> {"name": "min", "type": "long"},
> {"name": "max", "type": "long"},
> {"name": "sum", "type": "long"},
> {"name": "count", "type": "long"}
> ]
> }
> }
> }
> ]}
>
> Here is the code which we use to parse the data
>
> public static final MyPayLoad parseBinaryPayload(byte[] payload) {
> DatumReader<MyPayLoad> payloadReader = new
> SpecificDatumReader<>(MyPayLoad.class);
> Decoder decoder = DecoderFactory.get().binaryDecoder(payload, null);
> MyPayLoad myPayLoad = null;
> try {
> myPayLoad = payloadReader.read(null, decoder);
> } catch (IOException e) {
> logger.log(Level.SEVERE, e.getMessage(), e);
> }
>
> return myPayLoad;
> }
>
> Now i want to add one more field int the schema so the schema looks like
> below
>
> {
> "namespace": "xx.xxxx.xxxxx.xxxxx",
> "type": "record",
> "name": "MyPayLoad",
> "fields": [
> {"name": "filed1", "type": "string"},
> {"name": "filed2", "type": "long"},
> {"name": "filed3", "type": "boolean"},
> {
> "name" : "metrics",
> "type":
> {
> "type" : "array",
> "items":
> {
> "name": "MyRecord",
> "type": "record",
> "fields" :
> [
> {"name": "min", "type": "long"},
> {"name": "max", "type": "long"},
> {"name": "sum", "type": "long"},
> {"name": "count", "type": "long"}
> ]
> }
> }
> }
> {"name": "agentType", "type": ["null", "string"], "default":
> "APP_AGENT"}
> ]}
>
> Note the filed added and also the default is defined. The problem is that
> if we receive the data which was written using the older schema i get this
> error
>
> java.io.EOFException: null
> at org.apache.avro.io.BinaryDecoder.ensureBounds(BinaryDecoder.java:473)
> ~[avro-1.7.4.jar:1.7.4]
> at org.apache.avro.io.BinaryDecoder.readInt(BinaryDecoder.java:128)
> ~[avro-1.7.4.jar:1.7.4]
> at org.apache.avro.io.BinaryDecoder.readIndex(BinaryDecoder.java:423)
> ~[avro-1.7.4.jar:1.7.4]
> at
> org.apache.avro.io.ResolvingDecoder.doAction(ResolvingDecoder.java:229)
> ~[avro-1.7.4.jar:1.7.4]
> at org.apache.avro.io.parsing.Parser.advance(Parser.java:88)
> ~[avro-1.7.4.jar:1.7.4]
> at
> org.apache.avro.io.ResolvingDecoder.readIndex(ResolvingDecoder.java:206)
> ~[avro-1.7.4.jar:1.7.4]
> at
> org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:152)
> ~[avro-1.7.4.jar:1.7.4]
> at
> org.apache.avro.generic.GenericDatumReader.readRecord(GenericDatumReader.java:177)
> ~[avro-1.7.4.jar:1.7.4]
> at
> org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:148)
> ~[avro-1.7.4.jar:1.7.4]
> at
> org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:139)
> ~[avro-1.7.4.jar:1.7.4]
> at
> com.appdynamics.blitz.shared.util.XXXXXXXXXXXXX.parseBinaryPayload(BlitzAvroSharedUtil.java:38)
> ~[blitz-shared.jar:na]
>
> What i understood from this
> <https://martin.kleppmann.com/2012/12/05/schema-evolution-in-avro-protocol-buffers-thrift.html>
> document
> that this should have been backward compatible but somehow that doesn't
> seem to be the case. Any idea what i am doing wrong?
>
--
--
Cheers,
Praj
