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From: hvanhovell <git@git.apache.org>
To: reviews@spark.apache.org
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References: <git-pr-10896-spark@git.apache.org>
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Subject: [GitHub] spark pull request #10896: [SPARK-12978][SQL] Skip unnecessary final group-b...
Content-Type: text/plain
Message-Id: <20160822161227.E0BC4E055D@git1-us-west.apache.org>
Date: Mon, 22 Aug 2016 16:12:27 +0000 (UTC)
archived-at: Mon, 22 Aug 2016 16:12:30 -0000

Github user hvanhovell commented on a diff in the pull request:

    https://github.com/apache/spark/pull/10896#discussion_r75707785
  
    --- Diff: sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/AggUtils.scala ---
    @@ -27,26 +27,87 @@ import org.apache.spark.sql.execution.streaming.{StateStoreRestoreExec, StateSto
      */
     object AggUtils {
     
    -  def planAggregateWithoutPartial(
    +  private[execution] def isAggregate(operator: SparkPlan): Boolean = {
    +    operator.isInstanceOf[HashAggregateExec] || operator.isInstanceOf[SortAggregateExec]
    +  }
    +
    +  private[execution] def supportPartialAggregate(operator: SparkPlan): Boolean = {
    +    assert(isAggregate(operator))
    +    def supportPartial(exprs: Seq[AggregateExpression]) =
    +      exprs.map(_.aggregateFunction).forall(_.supportsPartial)
    +    operator match {
    +      case agg @ HashAggregateExec(_, _, aggregateExpressions, _, _, _, _) =>
    +        supportPartial(aggregateExpressions)
    +      case agg @ SortAggregateExec(_, _, aggregateExpressions, _, _, _, _) =>
    +        supportPartial(aggregateExpressions)
    +    }
    +  }
    +
    +  private def createPartialAggregateExec(
           groupingExpressions: Seq[NamedExpression],
           aggregateExpressions: Seq[AggregateExpression],
    -      resultExpressions: Seq[NamedExpression],
    -      child: SparkPlan): Seq[SparkPlan] = {
    +      child: SparkPlan): SparkPlan = {
    +    val groupingAttributes = groupingExpressions.map(_.toAttribute)
    +    val functionsWithDistinct = aggregateExpressions.filter(_.isDistinct)
    +    val partialAggregateExpressions = aggregateExpressions.map {
    +      case agg @ AggregateExpression(_, _, false, _) if functionsWithDistinct.length > 0 =>
    +        agg.copy(mode = PartialMerge)
    +      case agg =>
    +        agg.copy(mode = Partial)
    +    }
    +    val partialAggregateAttributes =
    +      partialAggregateExpressions.flatMap(_.aggregateFunction.aggBufferAttributes)
    +    val partialResultExpressions =
    +      groupingAttributes ++
    +        partialAggregateExpressions.flatMap(_.aggregateFunction.inputAggBufferAttributes)
     
    -    val completeAggregateExpressions = aggregateExpressions.map(_.copy(mode = Complete))
    -    val completeAggregateAttributes = completeAggregateExpressions.map(_.resultAttribute)
    -    SortAggregateExec(
    -      requiredChildDistributionExpressions = Some(groupingExpressions),
    +    createAggregateExec(
    +      requiredChildDistributionExpressions = None,
           groupingExpressions = groupingExpressions,
    -      aggregateExpressions = completeAggregateExpressions,
    -      aggregateAttributes = completeAggregateAttributes,
    -      initialInputBufferOffset = 0,
    -      resultExpressions = resultExpressions,
    -      child = child
    -    ) :: Nil
    +      aggregateExpressions = partialAggregateExpressions,
    +      aggregateAttributes = partialAggregateAttributes,
    +      initialInputBufferOffset = if (functionsWithDistinct.length > 0) {
    +        groupingExpressions.length + functionsWithDistinct.head.aggregateFunction.children.length
    +      } else {
    +        0
    +      },
    +      resultExpressions = partialResultExpressions,
    +      child = child)
    +  }
    +
    +  private def updateMergeAggregateMode(aggregateExpressions: Seq[AggregateExpression]) = {
    +    def updateMode(mode: AggregateMode) = mode match {
    +      case Partial => PartialMerge
    +      case Complete => Final
    +      case mode => mode
    +    }
    +    aggregateExpressions.map(e => e.copy(mode = updateMode(e.mode)))
    +  }
    +
    +  private[execution] def createPartialAggregate(operator: SparkPlan)
    --- End diff --
    
    Much better


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