HeartSaVioR commented on code in PR #45023:
URL: https://github.com/apache/spark/pull/45023#discussion_r1490104863
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python/pyspark/sql/datasource.py:
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@@ -298,6 +320,104 @@ def read(self, partition: InputPartition) ->
Iterator[Union[Tuple, Row]]:
...
+class DataSourceStreamReader(ABC):
+ """
+ A base class for streaming data source readers. Data source stream readers
are responsible
+ for outputting data from a streaming data source.
+
+ .. versionadded: 4.0.0
+ """
+
+ def initialOffset(self) -> dict:
+ """
+ Return the initial offset of the streaming data source.
+ A new streaming query starts reading data from the initial offset.
+ If Spark is restarting an existing query, it will restart from the
check-pointed offset
+ rather than the initial one.
+
+ Returns
+ -------
+ dict
+ A dict whose key and values are str type.
Review Comment:
We expect data source to know about its offset model - we pass a json format
of offset to specific data source, which is expected to be deserialized
successfully to its offset model. It will come to the runtime error if the json
format of offset and offset model aren't compatible, which I think Scala side
is doing the same.
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