Hi Paul Would you please share more information of the exception stack trace and the state descriptor of this map state with that window operator?
For all user-facing keyed state, the namespace serializer would always be VoidNamespaceSerializer. And only window state could have different name space serializer. Best Yun Tang ________________________________ From: Paul Lam <paullin3...@gmail.com> Sent: Tuesday, August 27, 2019 17:14 To: user <user@flink.apache.org> Cc: Tzu-Li (Gordon) Tai <tzuli...@apache.org> Subject: StateMigrationException thrown by state processor api Hi, I was using the new state processor api to read a savepoint produced by Flink 1.5.3, and got an StateMigrationException with message “For heap backends, the new namespace serializer must be compatible”. Concretely, the state I was trying to read is a MapState<String, Long> within a WindowOperator(TriggerContext) which is keyed by a string field, so the key & value data types and the corresponding serializers should be the basic one here (POJOSerializer). However, the error indicates the problem is about namespace serializer which I have not much knowledge about. So I dig a bit into the source code to find that the namespace serializer is not a highly configurable one, and both state processor api and the state to be read seem to use the same namespace serializer, `VoidNamespaceSerializer` (please correct me if I’m wrong). It still doesn’t explain why the error happened. Please point me to the right direction. Thanks a lot! Best, Paul Lam
