godfreyhe commented on a change in pull request #11260:
[FLINK-16344][table-planner-blink] Preserve nullability for nested types
URL: https://github.com/apache/flink/pull/11260#discussion_r389695314
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File path:
flink-table/flink-table-planner-blink/src/main/scala/org/apache/flink/table/planner/calcite/FlinkTypeFactory.scala
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@@ -293,6 +293,11 @@ class FlinkTypeFactory(typeSystem: RelDataTypeSystem)
extends JavaTypeFactoryImp
case it: TimeIndicatorRelDataType =>
new TimeIndicatorRelDataType(it.typeSystem, it.originalType,
isNullable, it.isEventTime)
+ // for nested rows we keep the nullability property,
+ // top-level rows fall back to Calcite's default handling
+ case rt: RelRecordType if rt.getStructKind ==
StructKind.PEEK_FIELDS_NO_EXPAND =>
Review comment:
I find that the comment in
`RelDataTypeFactoryImpl#createTypeWithNullability` says `According to the SQL
standard, nullability for struct types can be defined only for columns, which
translates to top level structs. Nested struct attributes are always nullable,
so in principle we could always set the nested attributes to be nullable.`
we do not follow the SQL standard here ?
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