liuyongvs commented on code in PR #3189:
URL: https://github.com/apache/calcite/pull/3189#discussion_r1197508002
##########
core/src/main/java/org/apache/calcite/sql/fun/SqlCastFunction.java:
##########
@@ -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:
after dig the code of spark, you are right, thanks.
I intuitively thought it was the latter.
```
test("element type nullability") {
val array = Literal.create(Seq("123", "true"),
ArrayType(StringType, containsNull = false))
// array element can be null after try_cast which violates the target
type.
val c1 = cast(array, ArrayType(BooleanType, containsNull = false))
assert(!c1.resolved)
val map = Literal.create(Map("a" -> "123", "b" -> "true"),
MapType(StringType, StringType, valueContainsNull = false))
// key can be null after try_cast which violates the map key requirement.
val c2 = cast(map, MapType(IntegerType, StringType, valueContainsNull =
true))
assert(!c2.resolved)
// map value can be null after try_cast which violates the target type.
val c3 = cast(map, MapType(StringType, IntegerType, valueContainsNull =
false))
assert(!c3.resolved)
val struct = Literal.create(
InternalRow(
UTF8String.fromString("123"),
UTF8String.fromString("true")),
new StructType()
.add("a", StringType, nullable = true)
.add("b", StringType, nullable = true))
// struct field `b` can be null after try_cast which violates the target
type.
val c4 = cast(struct, new StructType()
.add("a", BooleanType, nullable = true)
.add("b", BooleanType, nullable = false))
assert(!c4.resolved)
}
```
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