[FLINK-25930] Remove identity casting from ScalarOperatorGens

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Assignee: Unassigned
• Reporter: Marios Trivyzas
• Created: 02/Feb/22 14:48
• Updated: 04/Feb/22 13:09

Description

Following: https://github.com/apache/flink/pull/18582

we could remove the following code from ScalarOperatorGens:

 

 

case (_, _) if isInteroperable(operand.resultType, targetType) =>
operand.copy(resultType = targetType)
 

and use our IdentityCastRule instead but there is an issue.

 

Currently the isInteroperable allows casting between types with different nullability whereas the IdentityCastRule uses the LogicalTypeCasts#supportsAvoidingCast which in turn uses the CastAvoidanceChecker which doesn't allow to cast from a nullable type to the same but non-nullable type, i.e. INT -> INT NOT NULL

if (sourceType.isNullable() && !targetType.isNullable()
        || sourceType.getClass() != targetType.getClass()
        || // TODO drop this line once we remove legacy types
        sourceType.getTypeRoot() != targetType.getTypeRoot()) {
    return false;
}