add support for left semi join

Author: adrian-wang

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/joinTypes.scala

@@ -22,3 +22,4 @@ case object Inner extends JoinType
 case object LeftOuter extends JoinType
 case object RightOuter extends JoinType
 case object FullOuter extends JoinType
+case object LeftSemi extends JoinType

sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala

@@ -193,6 +193,7 @@ class SQLContext(@transient val sparkContext: SparkContext)
     val strategies: Seq[Strategy] =
       TakeOrdered ::
       PartialAggregation ::
+      LeftSemiJoin ::
       HashJoin ::
       ParquetOperations ::
       BasicOperators ::

sql/core/src/main/scala/org/apache/spark/sql/execution/SparkStrategies.scala

@@ -28,6 +28,22 @@ import org.apache.spark.sql.parquet._
 private[sql] abstract class SparkStrategies extends QueryPlanner[SparkPlan] {
   self: SQLContext#SparkPlanner =>
 
+  object LeftSemiJoin extends Strategy with PredicateHelper {
+    def apply(plan: LogicalPlan): Seq[SparkPlan] = plan match {
+      // Find leftsemi joins where at least some predicates can be evaluated by matching hash keys
+      // using the HashFilteredJoin pattern.
+      case HashFilteredJoin(LeftSemi, leftKeys, rightKeys, condition, left, right) =>
+        val semiJoin =
+          execution.LeftSemiJoinHash(leftKeys, rightKeys, BuildRight, planLater(left), planLater(right))
+        condition.map(Filter(_, semiJoin)).getOrElse(semiJoin) :: Nil
+      // no predicate can be evaluated by matching hash keys
+      case logical.Join(left, right, LeftSemi, condition) =>
+        execution.LeftSemiJoinBNL(
+          planLater(left), planLater(right), LeftSemi, condition)(sparkContext) :: Nil
+      case _ => Nil
+    }
+  }
+
   object HashJoin extends Strategy with PredicateHelper {
     def apply(plan: LogicalPlan): Seq[SparkPlan] = plan match {
       // Find inner joins where at least some predicates can be evaluated by matching hash keys

sql/core/src/main/scala/org/apache/spark/sql/execution/joins.scala

@@ -140,6 +140,150 @@ case class HashJoin(
   }
 }
 
+/**
+ * :: DeveloperApi ::
+ */
+@DeveloperApi
+case class LeftSemiJoinHash(
+                     leftKeys: Seq[Expression],
+                     rightKeys: Seq[Expression],
+                     buildSide: BuildSide,
+                     left: SparkPlan,
+                     right: SparkPlan) extends BinaryNode {
+
+  override def outputPartitioning: Partitioning = left.outputPartitioning
+
+  override def requiredChildDistribution =
+    ClusteredDistribution(leftKeys) :: ClusteredDistribution(rightKeys) :: Nil
+
+  val (buildPlan, streamedPlan) = buildSide match {
+    case BuildLeft => (left, right)
+    case BuildRight => (right, left)
+  }
+
+  val (buildKeys, streamedKeys) = buildSide match {
+    case BuildLeft => (leftKeys, rightKeys)
+    case BuildRight => (rightKeys, leftKeys)
+  }
+
+  def output = left.output
+
+  @transient lazy val buildSideKeyGenerator = new Projection(buildKeys, buildPlan.output)
+  @transient lazy val streamSideKeyGenerator =
+    () => new MutableProjection(streamedKeys, streamedPlan.output)
+
+  def execute() = {
+
+    buildPlan.execute().zipPartitions(streamedPlan.execute()) { (buildIter, streamIter) =>
+    // TODO: Use Spark's HashMap implementation.
+      val hashTable = new java.util.HashMap[Row, ArrayBuffer[Row]]()
+      var currentRow: Row = null
+
+      // Create a mapping of buildKeys -> rows
+      while (buildIter.hasNext) {
+        currentRow = buildIter.next()
+        val rowKey = buildSideKeyGenerator(currentRow)
+        if(!rowKey.anyNull) {
+          val existingMatchList = hashTable.get(rowKey)
+          val matchList = if (existingMatchList == null) {
+            val newMatchList = new ArrayBuffer[Row]()
+            hashTable.put(rowKey, newMatchList)
+            newMatchList
+          } else {
+            existingMatchList
+          }
+          matchList += currentRow.copy()
+        }
+      }
+
+      new Iterator[Row] {
+        private[this] var currentStreamedRow: Row = _
+        private[this] var currentHashMatched: Boolean = false
+
+        private[this] val joinKeys = streamSideKeyGenerator()
+
+        override final def hasNext: Boolean =
+          streamIter.hasNext && fetchNext()
+
+        override final def next() = {
+          currentStreamedRow
+        }
+
+        /**
+         * Searches the streamed iterator for the next row that has at least one match in hashtable.
+         *
+         * @return true if the search is successful, and false the streamed iterator runs out of
+         *         tuples.
+         */
+        private final def fetchNext(): Boolean = {
+          currentHashMatched = false
+          while (!currentHashMatched && streamIter.hasNext) {
+            currentStreamedRow = streamIter.next()
+            if (!joinKeys(currentStreamedRow).anyNull) {
+              currentHashMatched = true
+            }
+          }
+          currentHashMatched
+        }
+      }
+    }
+  }
+}
+
+/**
+ * :: DeveloperApi ::
+ */
+@DeveloperApi
+case class LeftSemiJoinBNL(
+    streamed: SparkPlan, broadcast: SparkPlan, joinType: JoinType, condition: Option[Expression])
+    (@transient sc: SparkContext)
+  extends BinaryNode {
+  // TODO: Override requiredChildDistribution.
+
+  override def outputPartitioning: Partitioning = streamed.outputPartitioning
+
+  override def otherCopyArgs = sc :: Nil
+
+  def output = left.output
+
+  /** The Streamed Relation */
+  def left = streamed
+  /** The Broadcast relation */
+  def right = broadcast
+
+  @transient lazy val boundCondition =
+    InterpretedPredicate(
+      condition
+        .map(c => BindReferences.bindReference(c, left.output ++ right.output))
+        .getOrElse(Literal(true)))
+
+
+  def execute() = {
+    val broadcastedRelation = sc.broadcast(broadcast.execute().map(_.copy()).collect().toIndexedSeq)
+
+    val streamedPlusMatches = streamed.execute().mapPartitions { streamedIter =>
+      val joinedRow = new JoinedRow
+
+      streamedIter.filter(streamedRow => {
+        var i = 0
+        var matched = false
+
+        while (i < broadcastedRelation.value.size && !matched) {
+          // TODO: One bitset per partition instead of per row.
+          val broadcastedRow = broadcastedRelation.value(i)
+          if (boundCondition(joinedRow(streamedRow, broadcastedRow))) {
+            matched = true
+          }
+          i += 1
+        }
+        matched
+      }).map(streamedRow => (streamedRow, null))
+    }
+
+    streamedPlusMatches.map(_._1)
+  }
+}
+
 /**
  * :: DeveloperApi ::
  */

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala

@@ -224,6 +224,7 @@ class HiveContext(sc: SparkContext) extends SQLContext(sc) {
       DataSinks,
       Scripts,
       PartialAggregation,
+      LeftSemiJoin,
       HashJoin,
       BasicOperators,
       CartesianProduct,

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala

@@ -680,6 +680,7 @@ private[hive] object HiveQl {
         case "TOK_RIGHTOUTERJOIN" => RightOuter
         case "TOK_LEFTOUTERJOIN" => LeftOuter
         case "TOK_FULLOUTERJOIN" => FullOuter
+        case "TOK_LEFTSEMIJOIN" => LeftSemi
       }
       assert(other.size <= 1, "Unhandled join clauses.")
       Join(nodeToRelation(relation1),

sql/hive/src/test/resources/golden/leftsemijoin-0-80b6466213face7fbcb0de044611e1f5

@@ -0,0 +1 @@
+0