[SPARK-29343][SQL] Eliminate sorts without limit in the subquery of Join/Aggregation

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala

@@ -97,7 +97,6 @@ abstract class Optimizer(catalogManager: CatalogManager)
         SimplifyBinaryComparison,
         ReplaceNullWithFalseInPredicate,
         PruneFilters,
-        EliminateSorts,
         SimplifyCasts,
         SimplifyCaseConversionExpressions,
         RewriteCorrelatedScalarSubquery,
@@ -174,8 +173,8 @@ abstract class Optimizer(catalogManager: CatalogManager)
     // idempotence enforcement on this batch. We thus make it FixedPoint(1) instead of Once.
     Batch("Join Reorder", FixedPoint(1),
       CostBasedJoinReorder) :+
-    Batch("Remove Redundant Sorts", Once,
-      RemoveRedundantSorts) :+
+    Batch("Eliminate Sorts", Once,
+      EliminateSorts) :+
     Batch("Decimal Optimizations", fixedPoint,
       DecimalAggregates) :+
     Batch("Object Expressions Optimization", fixedPoint,
@@ -953,26 +952,25 @@ object CombineFilters extends Rule[LogicalPlan] with PredicateHelper {
 }
 
 /**
- * Removes no-op SortOrder from Sort
+ * Removes Sort operation. This can happen:
+ * 1) if the sort is noop
+ * 2) if the child is already sorted
+ * 3) if there is another Sort operator separated by 0...n Project/Filter operators
+ * 4) if the Sort operator is within Join and without Limit
+ * 5) if the Sort operator is within GroupBy and the aggregate function is order irrelevant
  */
 object EliminateSorts extends Rule[LogicalPlan] {
   def apply(plan: LogicalPlan): LogicalPlan = plan transform {
     case s @ Sort(orders, _, child) if orders.isEmpty || orders.exists(_.child.foldable) =>
       val newOrders = orders.filterNot(_.child.foldable)
       if (newOrders.isEmpty) child else s.copy(order = newOrders)
-  }
-}
-
-/**
- * Removes redundant Sort operation. This can happen:
- * 1) if the child is already sorted
- * 2) if there is another Sort operator separated by 0...n Project/Filter operators
- */
-object RemoveRedundantSorts extends Rule[LogicalPlan] {
-  def apply(plan: LogicalPlan): LogicalPlan = plan transformDown {
     case Sort(orders, true, child) if SortOrder.orderingSatisfies(child.outputOrdering, orders) =>
       child
     case s @ Sort(_, _, child) => s.copy(child = recursiveRemoveSort(child))
+    case j @ Join(originLeft, originRight, _, cond, _) if cond.forall(_.deterministic) =>
+      j.copy(left = recursiveRemoveSort(originLeft), right = recursiveRemoveSort(originRight))
+    case g @ Aggregate(_, aggs, originChild) if isOrderIrrelevantAggs(aggs) =>
+      g.copy(child = recursiveRemoveSort(originChild))
   }
 
   def recursiveRemoveSort(plan: LogicalPlan): LogicalPlan = plan match {
@@ -987,6 +985,24 @@ object RemoveRedundantSorts extends Rule[LogicalPlan] {
     case f: Filter => f.condition.deterministic
     case _ => false
   }
+
+  def isOrderIrrelevantAggs(aggs: Seq[NamedExpression]): Boolean = {
+    def isOrderIrrelevantAggFunction(func: AggregateFunction): Boolean = func match {
+      case _: Sum => true
+      case _: Min => true
+      case _: Max => true
+      case _: Count => true
+      case _: Average => true
+      case _: CentralMomentAgg => true
+      case _ => false
+    }
+
+    aggs.flatMap { e =>
+      e.collect {
+        case ae: AggregateExpression => ae.aggregateFunction
+      }
+    }.forall(isOrderIrrelevantAggFunction)
+  }
 }
 
 /**

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/EliminateSortsSuite.scala

@@ -35,12 +35,22 @@ class EliminateSortsSuite extends PlanTest {
 
   object Optimize extends RuleExecutor[LogicalPlan] {
     val batches =
-      Batch("Eliminate Sorts", FixedPoint(10),
+      Batch("Default", FixedPoint(10),
         FoldablePropagation,
-        EliminateSorts) :: Nil
+        LimitPushDown) ::
+      Batch("Eliminate Sorts", Once,
+        EliminateSorts) ::
+      Batch("Collapse Project", Once,
+        CollapseProject) :: Nil
+  }
+
+  object PushDownOptimizer extends RuleExecutor[LogicalPlan] {
+    val batches =
+      Batch("Limit PushDown", FixedPoint(10), LimitPushDown) :: Nil
   }
 
   val testRelation = LocalRelation('a.int, 'b.int, 'c.int)
+  val testRelationB = LocalRelation('d.int)
 
   test("Empty order by clause") {
     val x = testRelation
@@ -83,4 +93,196 @@ class EliminateSortsSuite extends PlanTest {
 
     comparePlans(optimized, correctAnswer)
   }
+
+  test("remove redundant order by") {
+    val orderedPlan = testRelation.select('a, 'b).orderBy('a.asc, 'b.desc_nullsFirst)
+    val unnecessaryReordered = orderedPlan.limit(2).select('a).orderBy('a.asc, 'b.desc_nullsFirst)
+    val optimized = Optimize.execute(unnecessaryReordered.analyze)
+    val correctAnswer = orderedPlan.limit(2).select('a).analyze
+    comparePlans(Optimize.execute(optimized), correctAnswer)
+  }
+
+  test("do not remove sort if the order is different") {
+    val orderedPlan = testRelation.select('a, 'b).orderBy('a.asc, 'b.desc_nullsFirst)
+    val reorderedDifferently = orderedPlan.limit(2).select('a).orderBy('a.asc, 'b.desc)
+    val optimized = Optimize.execute(reorderedDifferently.analyze)
+    val correctAnswer = reorderedDifferently.analyze
+    comparePlans(optimized, correctAnswer)
+  }
+
+  test("filters don't affect order") {
+    val orderedPlan = testRelation.select('a, 'b).orderBy('a.asc, 'b.desc)
+    val filteredAndReordered = orderedPlan.where('a > Literal(10)).orderBy('a.asc, 'b.desc)
+    val optimized = Optimize.execute(filteredAndReordered.analyze)
+    val correctAnswer = orderedPlan.where('a > Literal(10)).analyze
+    comparePlans(optimized, correctAnswer)
+  }
+
+  test("limits don't affect order") {
+    val orderedPlan = testRelation.select('a, 'b).orderBy('a.asc, 'b.desc)
+    val filteredAndReordered = orderedPlan.limit(Literal(10)).orderBy('a.asc, 'b.desc)
+    val optimized = Optimize.execute(filteredAndReordered.analyze)
+    val correctAnswer = orderedPlan.limit(Literal(10)).analyze
+    comparePlans(optimized, correctAnswer)
+  }
+
+  test("different sorts are not simplified if limit is in between") {
+    val orderedPlan = testRelation.select('a, 'b).orderBy('b.desc).limit(Literal(10))
+      .orderBy('a.asc)
+    val optimized = Optimize.execute(orderedPlan.analyze)
+    val correctAnswer = orderedPlan.analyze
+    comparePlans(optimized, correctAnswer)
+  }
+
+  test("range is already sorted") {
+    val inputPlan = Range(1L, 1000L, 1, 10)
+    val orderedPlan = inputPlan.orderBy('id.asc)
+    val optimized = Optimize.execute(orderedPlan.analyze)
+    val correctAnswer = inputPlan.analyze
+    comparePlans(optimized, correctAnswer)
+
+    val reversedPlan = inputPlan.orderBy('id.desc)
+    val reversedOptimized = Optimize.execute(reversedPlan.analyze)
+    val reversedCorrectAnswer = reversedPlan.analyze
+    comparePlans(reversedOptimized, reversedCorrectAnswer)
+
+    val negativeStepInputPlan = Range(10L, 1L, -1, 10)
+    val negativeStepOrderedPlan = negativeStepInputPlan.orderBy('id.desc)
+    val negativeStepOptimized = Optimize.execute(negativeStepOrderedPlan.analyze)
+    val negativeStepCorrectAnswer = negativeStepInputPlan.analyze
+    comparePlans(negativeStepOptimized, negativeStepCorrectAnswer)
+  }
+
+  test("sort should not be removed when there is a node which doesn't guarantee any order") {
+    val orderedPlan = testRelation.select('a, 'b)
+    val groupedAndResorted = orderedPlan.groupBy('a)(sum('a)).orderBy('a.asc)
+    val optimized = Optimize.execute(groupedAndResorted.analyze)
+    val correctAnswer = groupedAndResorted.analyze
+    comparePlans(optimized, correctAnswer)
+  }
+
+  test("remove two consecutive sorts") {
+    val orderedTwice = testRelation.orderBy('a.asc).orderBy('b.desc)
+    val optimized = Optimize.execute(orderedTwice.analyze)
+    val correctAnswer = testRelation.orderBy('b.desc).analyze
+    comparePlans(optimized, correctAnswer)
+  }
+
+  test("remove sorts separated by Filter/Project operators") {
+    val orderedTwiceWithProject = testRelation.orderBy('a.asc).select('b).orderBy('b.desc)
+    val optimizedWithProject = Optimize.execute(orderedTwiceWithProject.analyze)
+    val correctAnswerWithProject = testRelation.select('b).orderBy('b.desc).analyze
+    comparePlans(optimizedWithProject, correctAnswerWithProject)
+
+    val orderedTwiceWithFilter =
+      testRelation.orderBy('a.asc).where('b > Literal(0)).orderBy('b.desc)
+    val optimizedWithFilter = Optimize.execute(orderedTwiceWithFilter.analyze)
+    val correctAnswerWithFilter = testRelation.where('b > Literal(0)).orderBy('b.desc).analyze
+    comparePlans(optimizedWithFilter, correctAnswerWithFilter)
+
+    val orderedTwiceWithBoth =
+      testRelation.orderBy('a.asc).select('b).where('b > Literal(0)).orderBy('b.desc)
+    val optimizedWithBoth = Optimize.execute(orderedTwiceWithBoth.analyze)
+    val correctAnswerWithBoth =
+      testRelation.select('b).where('b > Literal(0)).orderBy('b.desc).analyze
+    comparePlans(optimizedWithBoth, correctAnswerWithBoth)
+
+    val orderedThrice = orderedTwiceWithBoth.select(('b + 1).as('c)).orderBy('c.asc)
+    val optimizedThrice = Optimize.execute(orderedThrice.analyze)
+    val correctAnswerThrice = testRelation.select('b).where('b > Literal(0))
+      .select(('b + 1).as('c)).orderBy('c.asc).analyze
+    comparePlans(optimizedThrice, correctAnswerThrice)
+  }
+
+  test("remove orderBy in groupBy clause with count aggs") {
+    val projectPlan = testRelation.select('a, 'b)
+    val unnecessaryOrderByPlan = projectPlan.orderBy('a.asc, 'b.desc)
+    val groupByPlan = unnecessaryOrderByPlan.groupBy('a)(count(1))
+    val optimized = Optimize.execute(groupByPlan.analyze)
+    val correctAnswer = projectPlan.groupBy('a)(count(1)).analyze
+    comparePlans(Optimize.execute(optimized), correctAnswer)
+  }
+
+  test("remove orderBy in groupBy clause with sum aggs") {
+    val projectPlan = testRelation.select('a, 'b)
+    val unnecessaryOrderByPlan = projectPlan.orderBy('a.asc, 'b.desc)
+    val groupByPlan = unnecessaryOrderByPlan.groupBy('a)(sum('a))
+    val optimized = Optimize.execute(groupByPlan.analyze)
+    val correctAnswer = projectPlan.groupBy('a)(sum('a)).analyze
+    comparePlans(Optimize.execute(optimized), correctAnswer)
+  }
+
+  test("remove orderBy in groupBy clause with first aggs") {
+    val projectPlan = testRelation.select('a, 'b)
+    val orderByPlan = projectPlan.orderBy('a.asc, 'b.desc)
+    val groupByPlan = orderByPlan.groupBy('a)(first('a))
+    val optimized = Optimize.execute(groupByPlan.analyze)
+    val correctAnswer = groupByPlan.analyze
+    comparePlans(Optimize.execute(optimized), correctAnswer)
+  }
+
+  test("remove orderBy in groupBy clause with first and count aggs") {
+    val projectPlan = testRelation.select('a, 'b)
+    val orderByPlan = projectPlan.orderBy('a.asc, 'b.desc)
+    val groupByPlan = orderByPlan.groupBy('a)(first('a), count(1))
+    val optimized = Optimize.execute(groupByPlan.analyze)
+    val correctAnswer = groupByPlan.analyze
+    comparePlans(Optimize.execute(optimized), correctAnswer)
+  }
+
+  test("should not remove orderBy with limit in groupBy clause") {
+    val projectPlan = testRelation.select('a, 'b)
+    val orderByPlan = projectPlan.orderBy('a.asc, 'b.desc).limit(10)
+    val groupByPlan = orderByPlan.groupBy('a)(count(1))
+    val optimized = Optimize.execute(groupByPlan.analyze)
+    val correctAnswer = groupByPlan.analyze
+    comparePlans(Optimize.execute(optimized), correctAnswer)
+  }
+
+  test("remove orderBy in join clause") {
+    val projectPlan = testRelation.select('a, 'b)
+    val unnecessaryOrderByPlan = projectPlan.orderBy('a.asc, 'b.desc)
+    val projectPlanB = testRelationB.select('d)
+    val joinPlan = unnecessaryOrderByPlan.join(projectPlanB).select('a, 'd)
+    val optimized = Optimize.execute(joinPlan.analyze)
+    val correctAnswer = projectPlan.join(projectPlanB).select('a, 'd).analyze
+    comparePlans(Optimize.execute(optimized), correctAnswer)
+  }
+
+  test("should not remove orderBy with limit in join clause") {
+    val projectPlan = testRelation.select('a, 'b)
+    val orderByPlan = projectPlan.orderBy('a.asc, 'b.desc).limit(10)
+    val projectPlanB = testRelationB.select('d)
+    val joinPlan = orderByPlan.join(projectPlanB).select('a, 'd)
+    val optimized = Optimize.execute(joinPlan.analyze)
+    val correctAnswer = joinPlan.analyze
+    comparePlans(Optimize.execute(optimized), correctAnswer)
+  }
+
+  test("should not remove orderBy in left join clause if there is an outer limit") {
+    val projectPlan = testRelation.select('a, 'b)
+    val orderByPlan = projectPlan.orderBy('a.asc, 'b.desc)
+    val projectPlanB = testRelationB.select('d)
+    val joinPlan = orderByPlan
+      .join(projectPlanB, LeftOuter)
+      .limit(10)
+    val optimized = Optimize.execute(joinPlan.analyze)
+    val correctAnswer = PushDownOptimizer.execute(joinPlan.analyze)
+    comparePlans(Optimize.execute(optimized), correctAnswer)
+  }
+
+  test("remove orderBy in right join clause event if there is an outer limit") {
+    val projectPlan = testRelation.select('a, 'b)
+    val orderByPlan = projectPlan.orderBy('a.asc, 'b.desc)
+    val projectPlanB = testRelationB.select('d)
+    val joinPlan = orderByPlan
+      .join(projectPlanB, RightOuter)
+      .limit(10)
+    val optimized = Optimize.execute(joinPlan.analyze)
+    val noOrderByPlan = projectPlan
+      .join(projectPlanB, RightOuter)
+      .limit(10)
+    val correctAnswer = PushDownOptimizer.execute(noOrderByPlan.analyze)
+    comparePlans(Optimize.execute(optimized), correctAnswer)
+  }
 }