Thanks for Jane and Sergey's proposal!
+1 to correct the Table API behavior.
I have one question: Is the influence only limited to the RowType? Does the
Map or Array type have the same problems?
Best,
Shengkai
[DISCUSS][FLINK-31830] Align the Nullability Handling of ROW between SQL
and TableA
Jane Chan <qingyue....@gmail.com> 于2023年12月22日周五 17:40写道：
> Dear devs,
>
> Several issues [1][2][3] have been identified regarding the inconsistent
> treatment of ROW type nullability between SQL and TableAPI. However,
> addressing these discrepancies might necessitate updates to the public API.
> Therefore, I'm initiating this discussion to engage the community in
> forging a unified approach to resolve these challenges.
>
> To summarize, SQL prohibits ROW types such as ROW<a INT NOT NULL, b
> STRING>, which is implicitly rewritten to ROW<a INT, b STRING> by
> Calcite[4]. In contrast, TableAPI permits such types, resulting in
> inconsistency.
> [image: image.png]
> For a comprehensive issue breakdown, please refer to the comment of [1].
>
> According to CALCITE-2464[4], ROW<f0 INT NOT NULL> is not a valid type. As
> a result, the behavior of TableAPI is incorrect and needs to be consistent
> with SQL, which means the implantation for the following public API needs
> to be changed.
>
> - RowType#copy(boolean nullable) should also set the inner fields to
> null if nullable is true.
> - RowType's constructor should also check nullability.
> - FieldsDataType#nullable() should also set the inner fields to null.
>
> In addition to the necessary changes in the implementation of the
> aforementioned API, the semantics of the following API have also been
> impacted.
>
> - `DataTypes.ROW(DataTypes.FIELD("f0",
> DataTypes.INT().notNull())).notNull()` cannot create a type like `ROW<INT
> NOT NULL>NOT NULL`.
> - Idempotence for chained calls `notNull().nullable().notNull()` for
> `Row` cannot be maintained.
>
> Sergey and I have engaged in a discussion regarding the solution [1]. I'm
> interested in gathering additional perspectives on the fix.
>
> Look forward to your ideas!
>
> Best,
> Jane
>
>
> [1] https://issues.apache.org/jira/browse/FLINK-31830
> [2] https://issues.apache.org/jira/browse/FLINK-31829
> [3] https://issues.apache.org/jira/browse/FLINK-33217
> [4] https://issues.apache.org/jira/browse/CALCITE-2464
>
