[GitHub] [spark] cloud-fan commented on a change in pull request #27742: [SPARK-30991] Refactor AQE readers and RDDs

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cloud-fan commented on a change in pull request #27742: [SPARK-30991] Refactor AQE readers and RDDs
URL: https://github.com/apache/spark/pull/27742#discussion_r386206246
 
 

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 File path: sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/LocalShuffledRowRDD.scala
 ##########
 @@ -1,112 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.apache.spark.sql.execution.adaptive
-
-import scala.collection.mutable.ArrayBuffer
-
-import org.apache.spark._
-import org.apache.spark.rdd.RDD
-import org.apache.spark.sql.catalyst.InternalRow
-import org.apache.spark.sql.execution.metric.{SQLMetric, SQLShuffleReadMetricsReporter}
-
-/**
- * The [[Partition]] used by [[LocalShuffledRowRDD]].
- * @param mapIndex the index of mapper.
- * @param startPartition the start partition ID in mapIndex mapper.
- * @param endPartition the end partition ID in mapIndex mapper.
- */
-private final class LocalShuffledRowRDDPartition(
-    override val index: Int,
-    val mapIndex: Int,
-    val startPartition: Int,
-    val endPartition: Int) extends Partition {
-}
-
-/**
- * This is a specialized version of [[org.apache.spark.sql.execution.ShuffledRowRDD]]. This is used
- * in Spark SQL adaptive execution when a shuffle join is converted to broadcast join at runtime
- * because the map output of one input table is small enough for broadcast. This RDD represents the
- * data of another input table of the join that reads from shuffle. Each partition of the RDD reads
- * the whole data from just one mapper output locally. So actually there is no data transferred
- * from the network.
- *
- * This RDD takes a [[ShuffleDependency]] (`dependency`).
- *
- * The `dependency` has the parent RDD of this RDD, which represents the dataset before shuffle
- * (i.e. map output). Elements of this RDD are (partitionId, Row) pairs.
- * Partition ids should be in the range [0, numPartitions - 1].
- * `dependency.partitioner.numPartitions` is the number of pre-shuffle partitions. (i.e. the number
- * of partitions of the map output). The post-shuffle partition number is the same to the parent
- * RDD's partition number.
- *
- * `partitionStartIndicesPerMapper` specifies how to split the shuffle blocks of each mapper into
- * one or more partitions. For a mapper `i`, the `j`th partition includes shuffle blocks from
- * `partitionStartIndicesPerMapper[i][j]` to `partitionStartIndicesPerMapper[i][j+1]` (exclusive).
- */
-class LocalShuffledRowRDD(
-     var dependency: ShuffleDependency[Int, InternalRow, InternalRow],
-     metrics: Map[String, SQLMetric],
-     partitionStartIndicesPerMapper: Array[Array[Int]])
-  extends RDD[InternalRow](dependency.rdd.context, Nil) {
-
-  private[this] val numReducers = dependency.partitioner.numPartitions
-  private[this] val numMappers = dependency.rdd.partitions.length
-
-  override def getDependencies: Seq[Dependency[_]] = List(dependency)
-
-  override def getPartitions: Array[Partition] = {
-    val partitions = ArrayBuffer[LocalShuffledRowRDDPartition]()
-    for (mapIndex <- 0 until numMappers) {
-      (partitionStartIndicesPerMapper(mapIndex) :+ numReducers).sliding(2, 1).foreach {
-        case Array(start, end) =>
-          partitions += new LocalShuffledRowRDDPartition(partitions.length, mapIndex, start, end)
-      }
-    }
-    partitions.toArray
-  }
-
-  override def getPreferredLocations(partition: Partition): Seq[String] = {
-    val tracker = SparkEnv.get.mapOutputTracker.asInstanceOf[MapOutputTrackerMaster]
-    tracker.getMapLocation(dependency, partition.index, partition.index + 1)
 
 Review comment:
   Ah yes!

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