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https://issues.apache.org/jira/browse/FLINK-18316?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated FLINK-18316:
-----------------------------------
Labels: pull-request-available (was: )
> Add a dynamic state registration primitive for Stateful Functions
> -----------------------------------------------------------------
>
> Key: FLINK-18316
> URL: https://issues.apache.org/jira/browse/FLINK-18316
> Project: Flink
> Issue Type: New Feature
> Components: Stateful Functions
> Reporter: Tzu-Li (Gordon) Tai
> Assignee: Tzu-Li (Gordon) Tai
> Priority: Major
> Labels: pull-request-available
>
> Currently, using the {{PersistedValue}} / {{PersistedTable}} /
> {{PersistedAppendingBuffer}} primitives, the user can only eagerly define
> states prior to function instance activation using the {{Persisted}} field
> annotation.
> We propose to add a primitive that allows them to register states dynamically
> after activation (i.e. during runtime), along the lines of:
> {code}
> public MyStateFn implements StatefulFunction {
> @Persisted
> private final PersistedStateProvider provider = new
> PersistedStateProvider();
> public MyStateFn() {
> PersistedValue<String> valueState = provider.getValue(...);
> }
> void invoke(Object input) {
> PersistedValue<String> anotherValueState = provider.getValue(...);
> }
> }
> {code}
> Note how you can register state during instantiation (in the constructor) and
> in the invoke method. Both registrations should be picked up by the runtime
> and bound to Flink state.
> This will be useful for a few scenarios:
> - Could enable us to get rid of eager state spec definitions in the YAML
> modules for remote functions in the future.
> - Will allow new state to be registered in remote functions, without shutting
> down the StateFun cluster.
> - Moreover, this approach allows us to differentiate which functions have
> dynamic state and which ones have only eager state, which might be handy in
> the future in case there is a need to differentiate.
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