[SPARK-34677][SQL] Support the +/- operators over ANSI SQL intervals

### What changes were proposed in this pull request? Extend the `Add`, `Subtract` and `UnaryMinus` expression to support `DayTimeIntervalType` and `YearMonthIntervalType` added by #31614. Note: the expressions can throw the `overflow` exception independently from the SQL config `spark.sql.ansi.enabled`. In this way, the modified expressions always behave in the ANSI mode for the intervals. ### Why are the changes needed? To conform to the ANSI SQL standard which defines `-/+` over intervals: <img width="822" alt="Screenshot 2021-03-09 at 21 59 22" src="https://user-images.githubusercontent.com/1580697/110523128-bd50ea80-8122-11eb-9982-782da0088d27.png"> ### Does this PR introduce _any_ user-facing change? Should not since new types have not been released yet. ### How was this patch tested? By running new tests in the test suites: ``` $ build/sbt "test:testOnly *ArithmeticExpressionSuite" $ build/sbt "test:testOnly *ColumnExpressionSuite" ``` Closes #31789 from MaxGekk/add-subtruct-intervals. Authored-by: Max Gekk <max.gekk@gmail.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com>
2021-03-11 10:08:43 +00:00 · 2021-03-11 10:08:43 +00:00 · 9d3d25bca4
parent 5c4d8f9538
commit 9d3d25bca4
9 changed files with 106 additions and 25 deletions
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/arithmetic.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/arithmetic.scala
@ -83,12 +83,19 @@ case class UnaryMinus(
      val iu = IntervalUtils.getClass.getCanonicalName.stripSuffix("$")
      val method = if (failOnError) "negateExact" else "negate"
      defineCodeGen(ctx, ev, c => s"$iu.$method($c)")
+    case DayTimeIntervalType | YearMonthIntervalType =>
+      nullSafeCodeGen(ctx, ev, eval => {
+        val mathClass = classOf[Math].getName
+        s"${ev.value} = $mathClass.negateExact($eval);"
+      })
  }

  protected override def nullSafeEval(input: Any): Any = dataType match {
    case CalendarIntervalType if failOnError =>
      IntervalUtils.negateExact(input.asInstanceOf[CalendarInterval])
    case CalendarIntervalType => IntervalUtils.negate(input.asInstanceOf[CalendarInterval])
+    case DayTimeIntervalType => Math.negateExact(input.asInstanceOf[Long])
+    case YearMonthIntervalType => Math.negateExact(input.asInstanceOf[Int])
    case _ => numeric.negate(input)
  }

@ -185,6 +192,12 @@ abstract class BinaryArithmetic extends BinaryOperator with NullIntolerant {
    case CalendarIntervalType =>
      val iu = IntervalUtils.getClass.getCanonicalName.stripSuffix("$")
      defineCodeGen(ctx, ev, (eval1, eval2) => s"$iu.$calendarIntervalMethod($eval1, $eval2)")
+    case DayTimeIntervalType | YearMonthIntervalType =>
+      assert(exactMathMethod.isDefined,
+        s"The expression '$nodeName' must override the exactMathMethod() method " +
+        "if it is supposed to operate over interval types.")
+      val mathClass = classOf[Math].getName
+      defineCodeGen(ctx, ev, (eval1, eval2) => s"$mathClass.${exactMathMethod.get}($eval1, $eval2)")
    // byte and short are casted into int when add, minus, times or divide
    case ByteType | ShortType =>
      nullSafeCodeGen(ctx, ev, (eval1, eval2) => {
@ -267,6 +280,10 @@ case class Add(
    case CalendarIntervalType =>
      IntervalUtils.add(
        input1.asInstanceOf[CalendarInterval], input2.asInstanceOf[CalendarInterval])
+    case DayTimeIntervalType =>
+      Math.addExact(input1.asInstanceOf[Long], input2.asInstanceOf[Long])
+    case YearMonthIntervalType =>
+      Math.addExact(input1.asInstanceOf[Int], input2.asInstanceOf[Int])
    case _ => numeric.plus(input1, input2)
  }

@ -306,6 +323,10 @@ case class Subtract(
    case CalendarIntervalType =>
      IntervalUtils.subtract(
        input1.asInstanceOf[CalendarInterval], input2.asInstanceOf[CalendarInterval])
+    case DayTimeIntervalType =>
+      Math.subtractExact(input1.asInstanceOf[Long], input2.asInstanceOf[Long])
+    case YearMonthIntervalType =>
+      Math.subtractExact(input1.asInstanceOf[Int], input2.asInstanceOf[Int])
    case _ => numeric.minus(input1, input2)
  }

--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/AbstractDataType.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/AbstractDataType.scala
@ -82,7 +82,11 @@ private[sql] object TypeCollection {
   * Types that include numeric types and interval type. They are only used in unary_minus,
   * unary_positive, add and subtract operations.
   */
-  val NumericAndInterval = TypeCollection(NumericType, CalendarIntervalType)
+  val NumericAndInterval = TypeCollection(
+    NumericType,
+    CalendarIntervalType,
+    DayTimeIntervalType,
+    YearMonthIntervalType)

  def apply(types: AbstractDataType*): TypeCollection = new TypeCollection(types)

--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/ExpressionTypeCheckingSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/ExpressionTypeCheckingSuite.scala
@ -78,9 +78,9 @@ class ExpressionTypeCheckingSuite extends SparkFunSuite {
    assertErrorForDifferingTypes(BitwiseXor(Symbol("intField"), Symbol("booleanField")))

    assertError(Add(Symbol("booleanField"), Symbol("booleanField")),
-      "requires (numeric or interval) type")
+      "requires (numeric or interval or daytimeinterval or yearmonthinterval) type")
    assertError(Subtract(Symbol("booleanField"), Symbol("booleanField")),
-      "requires (numeric or interval) type")
+      "requires (numeric or interval or daytimeinterval or yearmonthinterval) type")
    assertError(Multiply(Symbol("booleanField"), Symbol("booleanField")), "requires numeric type")
    assertError(Divide(Symbol("booleanField"), Symbol("booleanField")),
      "requires (double or decimal) type")
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ArithmeticExpressionSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/ArithmeticExpressionSuite.scala
@ -18,6 +18,7 @@
 package org.apache.spark.sql.catalyst.expressions

 import java.sql.{Date, Timestamp}
+import java.time.{Duration, Period}

 import org.apache.spark.SparkFunSuite
 import org.apache.spark.sql.catalyst.InternalRow
@ -576,4 +577,43 @@ class ArithmeticExpressionSuite extends SparkFunSuite with ExpressionEvalHelper
      }
    }
  }
+
+  test("SPARK-34677: exact add and subtract of day-time and year-month intervals") {
+    Seq(true, false).foreach { failOnError =>
+      checkExceptionInExpression[ArithmeticException](
+        UnaryMinus(
+          Literal.create(Period.ofMonths(Int.MinValue), YearMonthIntervalType),
+          failOnError),
+        "overflow")
+      checkExceptionInExpression[ArithmeticException](
+        Subtract(
+          Literal.create(Period.ofMonths(Int.MinValue), YearMonthIntervalType),
+          Literal.create(Period.ofMonths(10), YearMonthIntervalType),
+          failOnError
+        ),
+        "overflow")
+      checkExceptionInExpression[ArithmeticException](
+        Add(
+          Literal.create(Period.ofMonths(Int.MaxValue), YearMonthIntervalType),
+          Literal.create(Period.ofMonths(10), YearMonthIntervalType),
+          failOnError
+        ),
+        "overflow")
+
+      checkExceptionInExpression[ArithmeticException](
+        Subtract(
+          Literal.create(Duration.ofDays(-106751991), DayTimeIntervalType),
+          Literal.create(Duration.ofDays(10), DayTimeIntervalType),
+          failOnError
+        ),
+        "overflow")
+      checkExceptionInExpression[ArithmeticException](
+        Add(
+          Literal.create(Duration.ofDays(106751991), DayTimeIntervalType),
+          Literal.create(Duration.ofDays(10), DayTimeIntervalType),
+          failOnError
+        ),
+        "overflow")
+    }
+  }
 }
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/types/DataTypeTestUtils.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/types/DataTypeTestUtils.scala
@ -52,7 +52,10 @@ object DataTypeTestUtils {
  /**
   * Instances of all [[NumericType]]s and [[CalendarIntervalType]]
   */
-  val numericAndInterval: Set[DataType] = numericTypeWithoutDecimal + CalendarIntervalType
+  val numericAndInterval: Set[DataType] = numericTypeWithoutDecimal ++ Set(
+    CalendarIntervalType,
+    DayTimeIntervalType,
+    YearMonthIntervalType)

  /**
   * All the types that support ordering
--- a/sql/core/src/test/resources/sql-tests/results/ansi/literals.sql.out
+++ b/sql/core/src/test/resources/sql-tests/results/ansi/literals.sql.out
@ -436,7 +436,7 @@ select +date '1999-01-01'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ DATE '1999-01-01')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'DATE '1999-01-01'' is of date type.; line 1 pos 7
+cannot resolve '(+ DATE '1999-01-01')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'DATE '1999-01-01'' is of date type.; line 1 pos 7


 -- !query
@ -445,7 +445,7 @@ select +timestamp '1999-01-01'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ TIMESTAMP '1999-01-01 00:00:00')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'TIMESTAMP '1999-01-01 00:00:00'' is of timestamp type.; line 1 pos 7
+cannot resolve '(+ TIMESTAMP '1999-01-01 00:00:00')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'TIMESTAMP '1999-01-01 00:00:00'' is of timestamp type.; line 1 pos 7


 -- !query
@ -462,7 +462,7 @@ select +map(1, 2)
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ map(1, 2))' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'map(1, 2)' is of map<int,int> type.; line 1 pos 7
+cannot resolve '(+ map(1, 2))' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'map(1, 2)' is of map<int,int> type.; line 1 pos 7


 -- !query
@ -471,7 +471,7 @@ select +array(1,2)
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ array(1, 2))' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'array(1, 2)' is of array<int> type.; line 1 pos 7
+cannot resolve '(+ array(1, 2))' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'array(1, 2)' is of array<int> type.; line 1 pos 7


 -- !query
@ -480,7 +480,7 @@ select +named_struct('a', 1, 'b', 'spark')
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ named_struct('a', 1, 'b', 'spark'))' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'named_struct('a', 1, 'b', 'spark')' is of struct<a:int,b:string> type.; line 1 pos 7
+cannot resolve '(+ named_struct('a', 1, 'b', 'spark'))' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'named_struct('a', 1, 'b', 'spark')' is of struct<a:int,b:string> type.; line 1 pos 7


 -- !query
@ -489,7 +489,7 @@ select +X'1'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ X'01')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'X'01'' is of binary type.; line 1 pos 7
+cannot resolve '(+ X'01')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'X'01'' is of binary type.; line 1 pos 7


 -- !query
@ -498,7 +498,7 @@ select -date '1999-01-01'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(- DATE '1999-01-01')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'DATE '1999-01-01'' is of date type.; line 1 pos 7
+cannot resolve '(- DATE '1999-01-01')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'DATE '1999-01-01'' is of date type.; line 1 pos 7


 -- !query
@ -507,7 +507,7 @@ select -timestamp '1999-01-01'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(- TIMESTAMP '1999-01-01 00:00:00')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'TIMESTAMP '1999-01-01 00:00:00'' is of timestamp type.; line 1 pos 7
+cannot resolve '(- TIMESTAMP '1999-01-01 00:00:00')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'TIMESTAMP '1999-01-01 00:00:00'' is of timestamp type.; line 1 pos 7


 -- !query
@ -516,4 +516,4 @@ select -x'2379ACFe'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(- X'2379ACFE')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'X'2379ACFE'' is of binary type.; line 1 pos 7
+cannot resolve '(- X'2379ACFE')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'X'2379ACFE'' is of binary type.; line 1 pos 7
--- a/sql/core/src/test/resources/sql-tests/results/literals.sql.out
+++ b/sql/core/src/test/resources/sql-tests/results/literals.sql.out
@ -436,7 +436,7 @@ select +date '1999-01-01'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ DATE '1999-01-01')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'DATE '1999-01-01'' is of date type.; line 1 pos 7
+cannot resolve '(+ DATE '1999-01-01')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'DATE '1999-01-01'' is of date type.; line 1 pos 7


 -- !query
@ -445,7 +445,7 @@ select +timestamp '1999-01-01'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ TIMESTAMP '1999-01-01 00:00:00')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'TIMESTAMP '1999-01-01 00:00:00'' is of timestamp type.; line 1 pos 7
+cannot resolve '(+ TIMESTAMP '1999-01-01 00:00:00')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'TIMESTAMP '1999-01-01 00:00:00'' is of timestamp type.; line 1 pos 7


 -- !query
@ -462,7 +462,7 @@ select +map(1, 2)
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ map(1, 2))' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'map(1, 2)' is of map<int,int> type.; line 1 pos 7
+cannot resolve '(+ map(1, 2))' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'map(1, 2)' is of map<int,int> type.; line 1 pos 7


 -- !query
@ -471,7 +471,7 @@ select +array(1,2)
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ array(1, 2))' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'array(1, 2)' is of array<int> type.; line 1 pos 7
+cannot resolve '(+ array(1, 2))' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'array(1, 2)' is of array<int> type.; line 1 pos 7


 -- !query
@ -480,7 +480,7 @@ select +named_struct('a', 1, 'b', 'spark')
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ named_struct('a', 1, 'b', 'spark'))' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'named_struct('a', 1, 'b', 'spark')' is of struct<a:int,b:string> type.; line 1 pos 7
+cannot resolve '(+ named_struct('a', 1, 'b', 'spark'))' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'named_struct('a', 1, 'b', 'spark')' is of struct<a:int,b:string> type.; line 1 pos 7


 -- !query
@ -489,7 +489,7 @@ select +X'1'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(+ X'01')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'X'01'' is of binary type.; line 1 pos 7
+cannot resolve '(+ X'01')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'X'01'' is of binary type.; line 1 pos 7


 -- !query
@ -498,7 +498,7 @@ select -date '1999-01-01'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(- DATE '1999-01-01')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'DATE '1999-01-01'' is of date type.; line 1 pos 7
+cannot resolve '(- DATE '1999-01-01')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'DATE '1999-01-01'' is of date type.; line 1 pos 7


 -- !query
@ -507,7 +507,7 @@ select -timestamp '1999-01-01'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(- TIMESTAMP '1999-01-01 00:00:00')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'TIMESTAMP '1999-01-01 00:00:00'' is of timestamp type.; line 1 pos 7
+cannot resolve '(- TIMESTAMP '1999-01-01 00:00:00')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'TIMESTAMP '1999-01-01 00:00:00'' is of timestamp type.; line 1 pos 7


 -- !query
@ -516,4 +516,4 @@ select -x'2379ACFe'
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve '(- X'2379ACFE')' due to data type mismatch: argument 1 requires (numeric or interval) type, however, 'X'2379ACFE'' is of binary type.; line 1 pos 7
+cannot resolve '(- X'2379ACFE')' due to data type mismatch: argument 1 requires (numeric or interval or daytimeinterval or yearmonthinterval) type, however, 'X'2379ACFE'' is of binary type.; line 1 pos 7
--- a/sql/core/src/test/resources/sql-tests/results/typeCoercion/native/windowFrameCoercion.sql.out
+++ b/sql/core/src/test/resources/sql-tests/results/typeCoercion/native/windowFrameCoercion.sql.out
@ -168,7 +168,7 @@ SELECT COUNT(*) OVER (PARTITION BY 1 ORDER BY cast(1 as string) DESC RANGE BETWE
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve 'RANGE BETWEEN CURRENT ROW AND CAST(1 AS STRING) FOLLOWING' due to data type mismatch: The data type of the upper bound 'string' does not match the expected data type '(numeric or interval)'.; line 1 pos 21
+cannot resolve 'RANGE BETWEEN CURRENT ROW AND CAST(1 AS STRING) FOLLOWING' due to data type mismatch: The data type of the upper bound 'string' does not match the expected data type '(numeric or interval or daytimeinterval or yearmonthinterval)'.; line 1 pos 21


 -- !query
@ -177,7 +177,7 @@ SELECT COUNT(*) OVER (PARTITION BY 1 ORDER BY cast('1' as binary) DESC RANGE BET
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve 'RANGE BETWEEN CURRENT ROW AND CAST(1 AS BINARY) FOLLOWING' due to data type mismatch: The data type of the upper bound 'binary' does not match the expected data type '(numeric or interval)'.; line 1 pos 21
+cannot resolve 'RANGE BETWEEN CURRENT ROW AND CAST(1 AS BINARY) FOLLOWING' due to data type mismatch: The data type of the upper bound 'binary' does not match the expected data type '(numeric or interval or daytimeinterval or yearmonthinterval)'.; line 1 pos 21


 -- !query
@ -186,7 +186,7 @@ SELECT COUNT(*) OVER (PARTITION BY 1 ORDER BY cast(1 as boolean) DESC RANGE BETW
 struct<>
 -- !query output
 org.apache.spark.sql.AnalysisException
-cannot resolve 'RANGE BETWEEN CURRENT ROW AND CAST(1 AS BOOLEAN) FOLLOWING' due to data type mismatch: The data type of the upper bound 'boolean' does not match the expected data type '(numeric or interval)'.; line 1 pos 21
+cannot resolve 'RANGE BETWEEN CURRENT ROW AND CAST(1 AS BOOLEAN) FOLLOWING' due to data type mismatch: The data type of the upper bound 'boolean' does not match the expected data type '(numeric or interval or daytimeinterval or yearmonthinterval)'.; line 1 pos 21


 -- !query
--- a/sql/core/src/test/scala/org/apache/spark/sql/ColumnExpressionSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/ColumnExpressionSuite.scala
@ -18,6 +18,7 @@
 package org.apache.spark.sql

 import java.sql.{Date, Timestamp}
+import java.time.{Duration, Period}
 import java.util.Locale

 import org.apache.hadoop.io.{LongWritable, Text}
@ -2375,4 +2376,16 @@ class ColumnExpressionSuite extends QueryTest with SharedSparkSession {
    assert(e2.getCause.isInstanceOf[RuntimeException])
    assert(e2.getCause.getMessage == "hello")
  }
+
+  test("SPARK-34677: negate/add/subtract year-month and day-time intervals") {
+    import testImplicits._
+    val df = Seq((Period.ofMonths(10), Duration.ofDays(10), Period.ofMonths(1), Duration.ofDays(1)))
+      .toDF("year-month-A", "day-time-A", "year-month-B", "day-time-B")
+    val negatedDF = df.select(-$"year-month-A", -$"day-time-A")
+    checkAnswer(negatedDF, Row(Period.ofMonths(-10), Duration.ofDays(-10)))
+    val addDF = df.select($"year-month-A" + $"year-month-B", $"day-time-A" + $"day-time-B")
+    checkAnswer(addDF, Row(Period.ofMonths(11), Duration.ofDays(11)))
+    val subDF = df.select($"year-month-A" - $"year-month-B", $"day-time-A" - $"day-time-B")
+    checkAnswer(subDF, Row(Period.ofMonths(9), Duration.ofDays(9)))
+  }
 }