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Quick tip: In theory, the implementation of AsyncStateOperator and SyncStateOperator differs only in their state handling. Their state schemas, business logic, and others are the same. Therefore, within the same Flink version, when the SQL and other Flink configurations remain unchanged, or when using the same compiled plan, users can freely switch between AsyncStateOperator and SyncStateOperator by toggling the configuration table.exec.async-state.enabled, as they are fully compatible. One known exception is that when after the SQL AsyncStateOperator supports in-flight checkpoints in FLIP-455[2], switching back and forth between aligned and unaligned checkpoints is not compatible, which is an expected behavior.
Changes relying on more internal state APIs
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