org.apache.spark.sql.execution.joins.LeftSemiJoinHash.scala Maven / Gradle / Ivy

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/*
 * 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,
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 * See the License for the specific language governing permissions and
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package org.apache.spark.sql.execution.joins

import org.apache.spark.rdd.RDD
import org.apache.spark.sql.catalyst.InternalRow
import org.apache.spark.sql.catalyst.expressions._
import org.apache.spark.sql.catalyst.plans.{LeftSemiJoin, LeftSemi, LeftAnti}
import org.apache.spark.sql.catalyst.plans.physical.{Partitioning, Distribution, ClusteredDistribution}
import org.apache.spark.sql.execution.{BinaryNode, SparkPlan}
import org.apache.spark.sql.execution.metric.SQLMetrics

/**
 * Build the right table's join keys into a HashSet, and iteratively go through the left
 * table, to find the if join keys are in the Hash set.
 */
case class LeftSemiJoinHash(
    leftKeys: Seq[Expression],
    rightKeys: Seq[Expression],
    left: SparkPlan,
    right: SparkPlan,
    condition: Option[Expression],
    jt: LeftSemiJoin) extends BinaryNode with HashSemiJoin {

  override private[sql] lazy val metrics = Map(
    "numLeftRows" -> SQLMetrics.createLongMetric(sparkContext, "number of left rows"),
    "numRightRows" -> SQLMetrics.createLongMetric(sparkContext, "number of right rows"),
    "numOutputRows" -> SQLMetrics.createLongMetric(sparkContext, "number of output rows"))

  override def outputPartitioning: Partitioning = left.outputPartitioning

  override def requiredChildDistribution: Seq[Distribution] =
    ClusteredDistribution(leftKeys) :: ClusteredDistribution(rightKeys) :: Nil

  protected override def doExecute(): RDD[InternalRow] = {
    val numLeftRows = longMetric("numLeftRows")
    val numRightRows = longMetric("numRightRows")
    val numOutputRows = longMetric("numOutputRows")

    right.execute().zipPartitions(left.execute()) { (buildIter, streamIter) =>
      if (condition.isEmpty) {
        val hashSet = buildKeyHashSet(buildIter, numRightRows)
        jt match {
          case LeftSemi => hashSemiJoin(streamIter, numLeftRows, hashSet, numOutputRows)
          case LeftAnti => hashAntiJoin(streamIter, numLeftRows, hashSet, numOutputRows)
        }
      } else {
        val hashRelation = HashedRelation(buildIter, numRightRows, rightKeyGenerator)
        jt match {
          case LeftSemi => hashSemiJoin(streamIter, numLeftRows, hashRelation, numOutputRows)
          case LeftAnti => hashAntiJoin(streamIter, numLeftRows, hashRelation, numOutputRows)
        }
      }
    }
  }
}