[SPARK-42876][SQL] DataType's physicalDataType should be private[sql]

### What changes were proposed in this pull request?

`physicalDataType` should not be a public API but be private[sql].

### Why are the changes needed?

This is to limit API scope to not expose unnecessary API to be public.

### Does this PR introduce _any_ user-facing change?

No since we have not released Spark 3.4.0 yet.

### How was this patch tested?

N/A

Closes apache#40499 from amaliujia/change_scope_of_physical_data_type.

Authored-by: Rui Wang <[email protected]>
Signed-off-by: Wenchen Fan <[email protected]>
(cherry picked from commit c9a530e)
Signed-off-by: Wenchen Fan <[email protected]>

Author: amaliujia

sql/catalyst/src/main/scala/org/apache/spark/sql/types/ArrayType.scala

@@ -91,7 +91,7 @@ case class ArrayType(elementType: DataType, containsNull: Boolean) extends DataT
    */
   override def defaultSize: Int = 1 * elementType.defaultSize
 
-  override def physicalDataType: PhysicalDataType =
+  private[sql] override def physicalDataType: PhysicalDataType =
     PhysicalArrayType(elementType, containsNull)
 
   override def simpleString: String = s"array<${elementType.simpleString}>"

sql/catalyst/src/main/scala/org/apache/spark/sql/types/BinaryType.scala

@@ -45,7 +45,7 @@ class BinaryType private() extends AtomicType {
    */
   override def defaultSize: Int = 100
 
-  override def physicalDataType: PhysicalDataType = PhysicalBinaryType
+  private[sql] override def physicalDataType: PhysicalDataType = PhysicalBinaryType
 
   private[spark] override def asNullable: BinaryType = this
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/types/BooleanType.scala

@@ -42,7 +42,7 @@ class BooleanType private() extends AtomicType {
    */
   override def defaultSize: Int = 1
 
-  override def physicalDataType: PhysicalDataType = PhysicalBooleanType
+  private[sql] override def physicalDataType: PhysicalDataType = PhysicalBooleanType
 
   private[spark] override def asNullable: BooleanType = this
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/types/ByteType.scala

@@ -45,7 +45,7 @@ class ByteType private() extends IntegralType {
    */
   override def defaultSize: Int = 1
 
-  override def physicalDataType: PhysicalDataType = PhysicalByteType
+  private[sql] override def physicalDataType: PhysicalDataType = PhysicalByteType
 
   override def simpleString: String = "tinyint"
 

sql/catalyst/src/main/scala/org/apache/spark/sql/types/CalendarIntervalType.scala

@@ -38,7 +38,7 @@ class CalendarIntervalType private() extends DataType {
 
   override def defaultSize: Int = 16
 
-  override def physicalDataType: PhysicalDataType = PhysicalCalendarIntervalType
+  private[sql] override def physicalDataType: PhysicalDataType = PhysicalCalendarIntervalType
 
   override def typeName: String = "interval"
 

sql/catalyst/src/main/scala/org/apache/spark/sql/types/CharType.scala

@@ -33,7 +33,7 @@ case class CharType(length: Int) extends AtomicType {
   private[sql] val ordering = implicitly[Ordering[InternalType]]
 
   override def defaultSize: Int = length
-  override def physicalDataType: PhysicalDataType = PhysicalStringType
+  private[sql] override def physicalDataType: PhysicalDataType = PhysicalStringType
   override def typeName: String = s"char($length)"
   override def toString: String = s"CharType($length)"
   private[spark] override def asNullable: CharType = this

sql/catalyst/src/main/scala/org/apache/spark/sql/types/DataType.scala

@@ -119,7 +119,7 @@ abstract class DataType extends AbstractDataType {
 
   override private[sql] def acceptsType(other: DataType): Boolean = sameType(other)
 
-  def physicalDataType: PhysicalDataType = UninitializedPhysicalType
+  private[sql] def physicalDataType: PhysicalDataType = UninitializedPhysicalType
 }
 
 

sql/catalyst/src/main/scala/org/apache/spark/sql/types/DateType.scala

@@ -47,7 +47,7 @@ class DateType private() extends DatetimeType {
    */
   override def defaultSize: Int = 4
 
-  override def physicalDataType: PhysicalDataType = PhysicalIntegerType
+  private[sql] override def physicalDataType: PhysicalDataType = PhysicalIntegerType
 
   private[spark] override def asNullable: DateType = this
 }

sql/catalyst/src/main/scala/org/apache/spark/sql/types/DayTimeIntervalType.scala

@@ -61,7 +61,7 @@ case class DayTimeIntervalType(startField: Byte, endField: Byte) extends AnsiInt
    */
   override def defaultSize: Int = 8
 
-  override def physicalDataType: PhysicalDataType = PhysicalLongType
+  private[sql] override def physicalDataType: PhysicalDataType = PhysicalLongType
 
   private[spark] override def asNullable: DayTimeIntervalType = this
 

sql/catalyst/src/main/scala/org/apache/spark/sql/types/DecimalType.scala

@@ -111,7 +111,8 @@ case class DecimalType(precision: Int, scale: Int) extends FractionalType {
    */
   override def defaultSize: Int = if (precision <= Decimal.MAX_LONG_DIGITS) 8 else 16
 
-  override def physicalDataType: PhysicalDataType = PhysicalDecimalType(precision, scale)
+  private[sql] override def physicalDataType: PhysicalDataType =
+    PhysicalDecimalType(precision, scale)
 
   override def simpleString: String = s"decimal($precision,$scale)"