Dian Fu created FLINK-41103:
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Summary: ValueState.update(None) attempts to serialize None
instead of clearing the state
Key: FLINK-41103
URL: https://issues.apache.org/jira/browse/FLINK-41103
Project: Flink
Issue Type: Bug
Components: API / Python
Reporter: Dian Fu
The ValueState update contract specifies that a null value removes the current
key's state. In PyFlink process mode, update(None) instead appends None to the
underlying Beam bag after clearing it.
Reproduction using integer ValueState without TTL:
1. Write an integer value and complete a bundle.
2. Call state.update(None).
3. Complete the next bundle.
Expected:
The bundle completes successfully and subsequent reads return None.
Actual:
The bundle flush fails with "struct.error: required argument is not an integer"
when the buffered None is serialized. Reading immediately after update(None)
may appear correct because the pending local value is None.
Root cause:
SynchronousValueRuntimeState.update() unconditionally calls
self._internal_state.add(value), including when value is None.
The affected implementation is in
flink-python/pyflink/fn_execution/state_impl.py. The null case should clear the
state without appending a value, while preserving the applicable flush policy.
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