raminqaf commented on code in PR #29202:
URL: https://github.com/apache/flink/pull/29202#discussion_r4064031402
##########
flink-table/flink-table-planner/src/main/java/org/apache/calcite/sql/fun/SqlCastFunction.java:
##########
@@ -159,6 +179,19 @@ private static RelDataType
createTypeWithNullabilityFromExpr(
boolean safe) {
boolean isNullable = expressionType.isNullable() || safe;
+ if (targetType.getSqlTypeName() == SqlTypeName.VARIANT) {
+ // A variant can be cast from any other type, and it inherits
+ // the nullability of the source.
+ // Note that the order of this test and the next one is important.
+ return typeFactory.createTypeWithNullability(targetType,
expressionType.isNullable());
+ }
+
+ if (expressionType.getSqlTypeName() == SqlTypeName.VARIANT) {
+ // A variant can be cast to any other type, but the result
+ // is always nullable, like in the case of a safe cast.
+ return typeFactory.createTypeWithNullability(targetType, true);
Review Comment:
One thing that got confused is that we have hardcoded nullability here. So
if I write something like:
```sql
CAST(PARSE_JSON('42') AS TINYINT NOT NULL)
```
I would get a nullable TINYINT. Is this the correct behavior we are seeking?
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