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https://issues.apache.org/jira/browse/FLINK-23143?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17529258#comment-17529258
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Hangxiang Yu commented on FLINK-23143:
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Maybe I missed something. So what do you mean about "store wrapping objects in
a new map keyed by state name" ?
In the solution, If we don't add a new state, could we avoid updating
_RegisteredKeyValueStateBackendMetaInfo_ which use an
_EagerlyRegisteredStateSerializerProvider_ that don't support to register a new
serializaer?
I mean adds
_getOrCreateKeyedState(RegisteredKeyValueStateBackendMetaInfo<N, T> metaInfo,
StateDescriptor<S, T> stateDesc)_
to _KeyedStateBackend_ so Chaneglog could use the method instead of
_getOrCreateKeyedState(TypeSerializer<N> namespaceSerializer,
StateDescriptor<S, T> stateDescriptor)_
when recovery because the pre method will register
_RegisteredKeyValueStateBackendMetaInfo_ which use an
_LazilyRegisteredStateSerializerProvider._
The proposal is simple and works but it adds a extra methods to
_KeyedStateBackend_ and other state backend have to implement it.
I think if your solution could solve the question I mentioned above, maybe it
will be better.
> Support state migration
> -----------------------
>
> Key: FLINK-23143
> URL: https://issues.apache.org/jira/browse/FLINK-23143
> Project: Flink
> Issue Type: Sub-task
> Components: Runtime / State Backends
> Reporter: Roman Khachatryan
> Priority: Minor
> Fix For: 1.16.0
>
>
> ChangelogKeyedStateBackend.getOrCreateKeyedState is currently used during
> recovery; on 1st user access, it doesn't update metadata nor migrate state
> (as opposed to other backends).
>
> The proposed solution is to
> # wrap serializers (and maybe other objects) in getOrCreateKeyedState
> # store wrapping objects in a new map keyed by state name
> # pass wrapped objects to delegatedBackend.createInternalState
> # on 1st user access, lookup wrapper and upgrade its wrapped serializer
> This should be done for both KV/PQ states.
>
> See also [https://github.com/apache/flink/pull/15420#discussion_r656934791]
>
> cc: [~yunta]
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