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On the other hand, integration with FLIP-158 would add allow "background" materialization capability, eliminating periodic slow full checkpoints (or more complex way to achieve this).

For such an integration:

1. notify on startup, IncHeapKeyedBackend notifies ChangelogStateBackend that sending changes is not neededno changes should be sent (to the changelog)
2. on checkpoint, ask HeapBackend ChangelogStateBackend asks IncHeapKeyedBackend to create an incremental checkpoint
3. on materialization, ask ChangelogStateBackend asks for a full snapshot

This integration is out of scope of this FLIP.

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The backend/new classes will reside in a new module under flink/flink-state-backends.

The refactorings are mostly to allow extension and customization.

Public Interfaces

Code: see Proposed changes

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