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https://issues.apache.org/jira/browse/FLINK-3201?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15132226#comment-15132226
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ASF GitHub Bot commented on FLINK-3201:
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Github user aljoscha closed the pull request at:
https://github.com/apache/flink/pull/1562
> Enhance Partitioned State Interface with State Types
> ----------------------------------------------------
>
> Key: FLINK-3201
> URL: https://issues.apache.org/jira/browse/FLINK-3201
> Project: Flink
> Issue Type: Sub-task
> Components: Streaming
> Affects Versions: 1.0.0
> Reporter: Aljoscha Krettek
> Assignee: Aljoscha Krettek
>
> We should enhance the partitioned state with different state types, so that
> the system knows about the semantics of the State. I propose for now:
> - ValueState, this behaves like the current OperatorState: state is one value
> that can be set and retrieved
> - ListState, state is a list that can be appended to and iterated over
> - ReducingState, state is one value that other values can be added to
> ListState and ReducingState would share a common superclass to allow them to
> be used in the same places. For example, the WindowOperator would use
> ReducingState and ListState interchangeably, depending on whether we have a
> ReduceFunction or not.
> These additions allow the system to be clever about how state is checkpointed
> in the future. Think ManageMemory/Out-of-core state and incremental
> checkpoints.
> Also, state should be scoped to both a key and a namespace. This will allow
> the WindowOperator to use the interface. Right now, WindowOperator has a
> custom state implementation that uses a two-level Map (by key and by window).
> In this case the window would be the namespace.
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