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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
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package org.apache.spark.sql.execution

import org.apache.spark.rdd.PartitionCoalescer
import org.apache.spark.rdd.RDD
import org.apache.spark.sql.catalyst.InternalRow
import org.apache.spark.sql.catalyst.expressions.Attribute
import org.apache.spark.sql.catalyst.expressions.SortOrder
import org.apache.spark.sql.catalyst.plans.physical.Partitioning
import org.apache.spark.sql.catalyst.plans.physical.SinglePartition
import org.apache.spark.sql.catalyst.plans.physical.UnknownPartitioning

case class OrderAwareCoalesceExec(
    numPartitions: Int,
    coalescer: PartitionCoalescer,
    child: SparkPlan) extends UnaryExecNode {

  override def output: Seq[Attribute] = child.output

  override def outputOrdering: Seq[SortOrder] = child.outputOrdering

  override def outputPartitioning: Partitioning = {
    if (numPartitions == 1) SinglePartition else UnknownPartitioning(numPartitions)
  }

  protected override def doExecute(): RDD[InternalRow] = {
    val result = child.execute()
    if (numPartitions == 1 && result.getNumPartitions < 1) {
      // make sure we don't output an RDD with 0 partitions,
      // when claiming that we have a `SinglePartition`
      // see CoalesceExec in Spark
      new CoalesceExec.EmptyRDDWithPartitions(sparkContext, numPartitions)
    } else {
      result.coalesce(numPartitions, shuffle = false, Some(coalescer))
    }
  }

  override protected def withNewChildInternal(newChild: SparkPlan): SparkPlan = {
    copy(child = newChild)
  }
}




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