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https://issues.apache.org/jira/browse/FLINK-11917?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tzu-Li (Gordon) Tai closed FLINK-11917.
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Resolution: Won't Fix
Subsumed by FLINK-12045. Closing.
> Allow state schema migration from Kryo to POJO / Avro
> -----------------------------------------------------
>
> Key: FLINK-11917
> URL: https://issues.apache.org/jira/browse/FLINK-11917
> Project: Flink
> Issue Type: Improvement
> Components: API / Type Serialization System
> Reporter: Tzu-Li (Gordon) Tai
> Priority: Major
>
> In Flink, it has been commonly advertised that users should try to avoid Kryo
> for state serialization since it doesn't work out-of-the-box well for schema
> evolution stories. Kryo, in the first place, wasn't designed with that in
> mind.
> In light of this, Flink should provide a migration path for state that were
> default to be serialized by the {{KryoSerializer}} to other serializers that
> now support better schema evolution capabilities, such as {{PojoSerializer}}
> and {{AvroSerializer}}.
> Essentially, what this means is that in the {{KryoSerializerSnapshot}}
> class's {{resolveSchemaCompatibility}} method, we identify if the new
> serializer is either {{PojoSerializer}} or {{AvroSerializer}}; if so, we
> return {{TypeSerializerSchemaCompatibility.compatibleAfterMigration()}} as
> the result.
> For the user, this would allow them to simply upgrade their state types to be
> Avro-generated {{SpecificRecord}} or a qualified POJO.
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