[SPARK-38434] Correct semantic of CheckAnalysis.getDataTypesAreCompatibleFn method

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.2.1
• Fix Version/s: 3.3.0
• Component/s: SQL
• Assignee: Tengfei Huang
• Reporter: Tengfei Huang
• Created: 07/Mar/22 11:11
• Updated: 07/Mar/22 14:17
• Resolved: 07/Mar/22 14:17

Description

Currently, in `CheckAnalysis` method getDataTypesAreCompatibleFn implemented as:

  private def getDataTypesAreCompatibleFn(plan: LogicalPlan): (DataType, DataType) => Boolean = {
    val isUnion = plan.isInstanceOf[Union]
    if (isUnion) {
      (dt1: DataType, dt2: DataType) =>
        !DataType.equalsStructurally(dt1, dt2, true)
    } else {
      // SPARK-18058: we shall not care about the nullability of columns
      (dt1: DataType, dt2: DataType) =>
        TypeCoercion.findWiderTypeForTwo(dt1.asNullable, dt2.asNullable).isEmpty
    }
  }

Return false when data types are compatible, otherwise return true, which is pretty confusing.

Issue Links

• links to: [Github] Pull Request #35752 (ivoson)
• links to: [Github] Pull Request #35752 (ivoson)