libenchao commented on code in PR #3189:
URL: https://github.com/apache/calcite/pull/3189#discussion_r1189294026
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core/src/main/java/org/apache/calcite/sql/fun/SqlCastFunction.java:
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@@ -122,8 +128,50 @@ static SqlReturnTypeInference returnTypeInference(boolean
safe) {
/** Derives the type of "CAST(expression AS targetType)". */
public static RelDataType deriveType(RelDataTypeFactory typeFactory,
RelDataType expressionType, RelDataType targetType, boolean safe) {
- return typeFactory.createTypeWithNullability(targetType,
- expressionType.isNullable() || safe);
+ return createTypeWithNullabilityFromExpr(typeFactory, expressionType,
targetType, safe);
+ }
+
+ public static RelDataType
createTypeWithNullabilityFromExpr(RelDataTypeFactory typeFactory,
+ RelDataType expressionType, RelDataType targetType, boolean safe) {
+ boolean isn = expressionType.isNullable() || safe;
+
+ if (isCollection(expressionType)) {
+ RelDataType expressionElementType = expressionType.getComponentType();
+ RelDataType targetElementType = targetType.getComponentType();
+ RelDataType newElementType =
+ createTypeWithNullabilityFromExpr(typeFactory,
expressionElementType, targetElementType, false);
Review Comment:
This is not what I meant to say.
Take a example, `ARRAY<VARCHAR NOT NULL> NOT NULL`, safe_cast it to
`ARRAY<INT NULLABLE> NULLABLE`, what should the result be? IMO, the inner type
should be `NULLABLE` because it may produce `null`s.
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