Github user marmbrus commented on a diff in the pull request: https://github.com/apache/spark/pull/5208#discussion_r28287371 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/execution/joins/SortMergeJoin.scala --- @@ -0,0 +1,172 @@ +/* + * 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.joins + +import java.util.NoSuchElementException + +import org.apache.spark.annotation.DeveloperApi +import org.apache.spark.rdd.RDD +import org.apache.spark.sql.Row +import org.apache.spark.sql.catalyst.expressions._ +import org.apache.spark.sql.catalyst.plans._ +import org.apache.spark.sql.catalyst.plans.physical._ +import org.apache.spark.sql.execution.{BinaryNode, SparkPlan} +import org.apache.spark.util.collection.CompactBuffer + +/** + * :: DeveloperApi :: + * Performs an sort merge join of two child relations. + */ +@DeveloperApi +case class SortMergeJoin( + leftKeys: Seq[Expression], + rightKeys: Seq[Expression], + left: SparkPlan, + right: SparkPlan) extends BinaryNode { + + override def output: Seq[Attribute] = left.output ++ right.output + + override def outputPartitioning: Partitioning = left.outputPartitioning + + override def requiredChildDistribution: Seq[Distribution] = + ClusteredDistribution(leftKeys) :: ClusteredDistribution(rightKeys) :: Nil + + private val orders: Seq[SortOrder] = leftKeys.zipWithIndex.map { + case(expr, index) => SortOrder(BoundReference(index, expr.dataType, expr.nullable), Ascending) + } + // this is to manually construct an ordering that can be used to compare keys from both sides + private val keyOrdering: RowOrdering = new RowOrdering(orders) --- End diff -- This is much clearer, thank you! However, I'd like to hide the `BoundReference` creation a little more. What do you think about adding a constructor to `RowOrdering` that takes `Seq[DataType]` and using that here. This is purely a style thing, but I think its important to hide the concept of `BoundReference`s as much as possible.
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