Hi Petter,

which state backend are you using in your case? I think there is no quick solution for your problem because a proper schema evolution story is on the roadmap for Flink 1.6.

Would it work to change the serial version id of the generated Avro class as a temporary workaround?

Regards,
Timo


Am 18.04.18 um 14:21 schrieb Timo Walther:
Thank you. Maybe we already identified the issue (see https://issues.apache.org/jira/browse/FLINK-9202). I will use your code to verify it.

Regards,
Timo


Am 18.04.18 um 14:07 schrieb Petter Arvidsson:
Hi Timo,

Please find the generated class (for the second schema) attached.

Regards,
Petter

On Wed, Apr 18, 2018 at 11:32 AM, Timo Walther <twalthr@apache.org> wrote:
Hi Petter,

could you share the source code of the class that Avro generates out of this schema?

Thank you.

Regards,
Timo

Am 18.04.18 um 11:00 schrieb Petter Arvidsson:
Hello everyone,

I am trying to figure out how to set up Flink with Avro for state management (especially the content of snapshots) to enable state migrations (e.g. adding a nullable fields to a class). So far, in version 1.4.2, I tried to explicitly provide an instance of "new AvroTypeInfo(Accumulator.getClass())" where accumulator is a very simple Avro generated SpecificRecordBase of the following schema:

{"namespace": "io.relayr.flink",
 "type": "record",
 "name": "Accumulator",
 "fields": [
     {"name": "accumulator", "type": "int"}
 ]
}

This successfully saves the state to the snapshot. When I then try to load the snapshot with an updated schema (adding the nullable field) it fails. Schema looks like this:

{"namespace": "io.relayr.flink",
 "type": "record",
 "name": "Accumulator",
 "fields": [
     {"name": "accumulator", "type": "int"},
     {"name": "newStuff", "type": ["int", "null"]}
 ]
}

When I try to restart the Job from the snapshot, I get the following exception:
2018-04-17 09:35:23,519 WARN  org.apache.flink.api.common.typeutils.TypeSerializerSerializationUtil  - Deserialization of serializer errored; replacing with null.
java.io.IOException: Unloadable class for type serializer.
...
Caused by: java.io.InvalidClassException: io.relayr.flink.Accumulator; local class incompatible: stream classdesc serialVersionUID = -3555733236161157838, local class serialVersionUID = 5291033088112484292

Which is true, Avro tools do generate a new serialization ID for the bean, I just didn't expect it to be used and expected the Avro schema to be used instead? Did anyone get this working? What am I getting wrong?

Best regards,
Petter