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https://issues.apache.org/jira/browse/FLINK-40296?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated FLINK-40296:
-----------------------------------
    Labels: pull-request-available  (was: )

> Add an object-level migrate hook to TypeSerializerSnapshot
> ----------------------------------------------------------
>
>                 Key: FLINK-40296
>                 URL: https://issues.apache.org/jira/browse/FLINK-40296
>             Project: Flink
>          Issue Type: Sub-task
>          Components: API / Type Serialization System
>            Reporter: Weiqing Yang
>            Priority: Major
>              Labels: pull-request-available
>
> FLIP-527 needs a way for a serializer snapshot to transform an 
> already-deserialized state value from the schema it was written with into the 
> schema the current serializer expects.
>   This adds a single default method to TypeSerializerSnapshot:
>   {code:java}
>   default T migrate(TypeSerializerSnapshot<T> oldSerializerSnapshot, T value) 
> {
>       return value;
>   }
>   {code}
>   Like resolveSchemaCompatibility, it is invoked on the new snapshot and 
> receives the old snapshot as its argument. The default returns the value 
> unchanged, so behavior is unaffected for
>   every existing serializer: a value deserialized with the prior serializer 
> is structurally compatible with the current one and can be re-serialized as 
> is.
>   Serializers whose in-memory representation is coupled to the schema 
> override it. The RowData serializer does so in a follow-up subtask, remapping 
> fields by name.
>   FLIP-527: 
> https://cwiki.apache.org/confluence/spaces/FLINK/pages/353601981/FLIP-527+State+Schema+Evolution+for+RowData



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