Implement the local intersect operator

sql/core/src/main/scala/org/apache/spark/sql/execution/local/IntersectNode.scala

@@ -0,0 +1,61 @@
+/*
+* 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.local
+
+import scala.collection.mutable
+
+import org.apache.spark.sql.catalyst.InternalRow
+import org.apache.spark.sql.catalyst.expressions.Attribute
+
+case class IntersectNode(left: LocalNode, right: LocalNode) extends BinaryLocalNode {
+
+  override def output: Seq[Attribute] = left.output
+
+  private[this] var leftRows: mutable.HashSet[InternalRow] = _
+
+  private[this] var currentRow: InternalRow = _
+
+  override def open(): Unit = {
+    left.open()
+    leftRows = mutable.HashSet[InternalRow]()
+    while (left.next()) {
+      leftRows += left.fetch().copy()
+    }
+    left.close()
+    right.open()
+  }
+
+  override def next(): Boolean = {
+    currentRow = null
+    while (currentRow == null && right.next()) {
+      currentRow = right.fetch()
+      if (!leftRows.contains(currentRow)) {
+        currentRow = null
+      }
+    }
+    currentRow != null
+  }
+
+  override def fetch(): InternalRow = currentRow
+
+  override def close(): Unit = {
+    left.close()
+    right.close()
+  }
+
+}

sql/core/src/test/scala/org/apache/spark/sql/execution/local/IntersectNodeSuite.scala

@@ -0,0 +1,33 @@
+/*
+* 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.local
+
+class IntersectNodeSuite extends LocalNodeTest {
+
+  test("basic") {
+    val input1 = (1 to 10).map(i => (i, i.toString)).toDF("key", "value")
+    val input2 = (1 to 10).filter(_ % 2 == 0).map(i => (i, i.toString)).toDF("key", "value")
+
+    checkAnswer2(
+      input1,
+      input2,
+      (node1, node2) => IntersectNode(node1, node2),
+      input1.intersect(input2).collect()
+    )
+  }
+}