Github user yhuai commented on a diff in the pull request:
https://github.com/apache/spark/pull/7904#discussion_r36697062
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/joins/SortMergeOuterJoin.scala
---
@@ -0,0 +1,251 @@
+/*
+ * 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 org.apache.spark.annotation.DeveloperApi
+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.{JoinType, LeftOuter,
RightOuter}
+import org.apache.spark.sql.catalyst.plans.physical._
+import org.apache.spark.sql.execution.{BinaryNode, RowIterator, SparkPlan}
+
+/**
+ * :: DeveloperApi ::
+ * Performs an sort merge outer join of two child relations.
+ *
+ * Note: this does not support full outer join yet; see SPARK-9730 for
progress on this.
+ */
+@DeveloperApi
+case class SortMergeOuterJoin(
+ leftKeys: Seq[Expression],
+ rightKeys: Seq[Expression],
+ joinType: JoinType,
+ condition: Option[Expression],
+ left: SparkPlan,
+ right: SparkPlan) extends BinaryNode {
+
+ override def output: Seq[Attribute] = {
+ joinType match {
+ case LeftOuter =>
+ left.output ++ right.output.map(_.withNullability(true))
+ case RightOuter =>
+ left.output.map(_.withNullability(true)) ++ right.output
+ case x =>
+ throw new IllegalArgumentException(
+ s"${getClass.getSimpleName} should not take $x as the JoinType")
+ }
+ }
+
+ override def outputPartitioning: Partitioning = joinType match {
+ // For left and right outer joins, the output is partitioned by the
streamed input's join keys.
+ case LeftOuter => left.outputPartitioning
+ case RightOuter => right.outputPartitioning
+ case x =>
+ throw new IllegalArgumentException(
+ s"${getClass.getSimpleName} should not take $x as the JoinType")
+ }
+
+ override def outputOrdering: Seq[SortOrder] = joinType match {
+ // For left and right outer joins, the output is ordered by the
streamed input's join keys.
+ case LeftOuter => requiredOrders(leftKeys)
+ case RightOuter => requiredOrders(rightKeys)
+ case x => throw new IllegalArgumentException(
+ s"SortMergeOuterJoin should not take $x as the JoinType")
+ }
+
+ override def requiredChildDistribution: Seq[Distribution] =
+ ClusteredDistribution(leftKeys) :: ClusteredDistribution(rightKeys) ::
Nil
+
+ override def requiredChildOrdering: Seq[Seq[SortOrder]] =
+ requiredOrders(leftKeys) :: requiredOrders(rightKeys) :: Nil
+
+ private def requiredOrders(keys: Seq[Expression]): Seq[SortOrder] = {
+ // This must be ascending in order to agree with the `keyOrdering`
defined in `doExecute()`.
+ keys.map(SortOrder(_, Ascending))
+ }
+
+ private def isUnsafeMode: Boolean = {
+ (codegenEnabled && unsafeEnabled
+ && UnsafeProjection.canSupport(leftKeys)
+ && UnsafeProjection.canSupport(rightKeys)
+ && UnsafeProjection.canSupport(schema))
+ }
+
+ override def outputsUnsafeRows: Boolean = isUnsafeMode
+ override def canProcessUnsafeRows: Boolean = isUnsafeMode
+ override def canProcessSafeRows: Boolean = !isUnsafeMode
+
+ private def createLeftKeyGenerator(): Projection = {
+ if (isUnsafeMode) {
+ UnsafeProjection.create(leftKeys, left.output)
+ } else {
+ newProjection(leftKeys, left.output)
+ }
+ }
+
+ private def createRightKeyGenerator(): Projection = {
+ if (isUnsafeMode) {
+ UnsafeProjection.create(rightKeys, right.output)
+ } else {
+ newProjection(rightKeys, right.output)
+ }
+ }
+
+ override def doExecute(): RDD[InternalRow] = {
+ left.execute().zipPartitions(right.execute()) { (leftIter, rightIter)
=>
+ // An ordering that can be used to compare keys from both sides.
+ val keyOrdering =
newNaturalAscendingOrdering(leftKeys.map(_.dataType))
+ val boundCondition: (InternalRow) => Boolean = {
+ condition.map { cond =>
+ newPredicate(cond, left.output ++ right.output)
+ }.getOrElse {
+ (r: InternalRow) => true
+ }
+ }
+ val resultProj: InternalRow => InternalRow = {
+ if (isUnsafeMode) {
+ UnsafeProjection.create(schema)
+ } else {
+ identity[InternalRow]
+ }
+ }
+
+ joinType match {
+ case LeftOuter =>
+ val smjScanner = new SortMergeJoinScanner(
+ streamedKeyGenerator = createLeftKeyGenerator(),
+ bufferedKeyGenerator = createRightKeyGenerator(),
+ keyOrdering,
+ streamedIter = RowIterator.fromScala(leftIter),
+ bufferedIter = RowIterator.fromScala(rightIter)
+ )
+ val rightNullRow = new GenericInternalRow(right.output.length)
+ new LeftOuterIterator(smjScanner, rightNullRow, boundCondition,
resultProj).toScala
+
+ case RightOuter =>
+ val smjScanner = new SortMergeJoinScanner(
+ streamedKeyGenerator = createRightKeyGenerator(),
+ bufferedKeyGenerator = createLeftKeyGenerator(),
+ keyOrdering,
+ streamedIter = RowIterator.fromScala(rightIter),
+ bufferedIter = RowIterator.fromScala(leftIter)
+ )
+ val leftNullRow = new GenericInternalRow(left.output.length)
+ new RightOuterIterator(smjScanner, leftNullRow, boundCondition,
resultProj).toScala
+
+ case x =>
+ throw new IllegalArgumentException(
+ s"SortMergeOuterJoin should not take $x as the JoinType")
+ }
+ }
+ }
+}
+
+
+private class LeftOuterIterator(
+ smjScanner: SortMergeJoinScanner,
+ rightNullRow: InternalRow,
+ boundCondition: InternalRow => Boolean,
+ resultProj: InternalRow => InternalRow
+ ) extends RowIterator {
+ private[this] val joinedRow: JoinedRow = new JoinedRow()
+ private[this] var rightIdx: Int = 0
+ assert(smjScanner.getBufferedMatches.length == 0)
+
+ private def advanceLeft(): Boolean = {
+ rightIdx = 0
+ if (smjScanner.findNextOuterJoinRows()) {
+ joinedRow.withLeft(smjScanner.getStreamedRow)
+ if (smjScanner.getBufferedMatches.isEmpty) {
+ // There are no matching right rows, so return nulls for the right
row
+ joinedRow.withRight(rightNullRow)
+ } else {
+ // Find the next row from the right input that satisfied the bound
condition
+ if (!advanceRightUntilBoundConditionSatisfied()) {
+ joinedRow.withRight(rightNullRow)
+ }
+ }
+ true
+ } else {
+ // Left input has been exhausted
+ false
+ }
+ }
+
+ private def advanceRightUntilBoundConditionSatisfied(): Boolean = {
+ var foundMatch: Boolean = false
+ if (!foundMatch && rightIdx < smjScanner.getBufferedMatches.length) {
+ foundMatch =
boundCondition(joinedRow.withRight(smjScanner.getBufferedMatches(rightIdx)))
+ rightIdx += 1
+ }
+ foundMatch
+ }
+
+ override def advanceNext(): Boolean = {
+ advanceRightUntilBoundConditionSatisfied() || advanceLeft()
+ }
+
+ override def getRow: InternalRow = resultProj(joinedRow)
+}
+
+private class RightOuterIterator(
+ smjScanner: SortMergeJoinScanner,
+ leftNullRow: InternalRow,
+ boundCondition: InternalRow => Boolean,
+ resultProj: InternalRow => InternalRow
+ ) extends RowIterator {
+ private[this] val joinedRow: JoinedRow = new JoinedRow()
+ private[this] var leftIdx: Int = 0
+ assert(smjScanner.getBufferedMatches.length == 0)
+
+ private def advanceRight(): Boolean = {
+ leftIdx = 0
+ if (smjScanner.findNextOuterJoinRows()) {
+ joinedRow.withRight(smjScanner.getStreamedRow)
+ if (smjScanner.getBufferedMatches.isEmpty) {
+ // There are no matching left rows, so return nulls for the left
row
+ joinedRow.withLeft(leftNullRow)
+ } else {
+ // Find the next row from the left input that satisfied the bound
condition
+ if (!advanceLeftUntilBoundConditionSatisfied()) {
+ joinedRow.withLeft(leftNullRow)
+ }
+ }
+ true
+ } else {
+ // Right input has been exhausted
+ false
+ }
+ }
+
+ private def advanceLeftUntilBoundConditionSatisfied(): Boolean = {
+ var foundMatch: Boolean = false
+ if (!foundMatch && leftIdx < smjScanner.getBufferedMatches.length) {
--- End diff --
Use `while` loop at here?
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