[SPARK-2428][SQL] Add except and intersect methods to SchemaRDD.

Author: Takuya UESHIN <ueshin@happy-camper.st>

Closes #1355 from ueshin/issues/SPARK-2428 and squashes the following commits:

b6fa264 [Takuya UESHIN] Add except and intersect methods to SchemaRDD.

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

@@ -256,6 +256,26 @@ class SchemaRDD(
   def unionAll(otherPlan: SchemaRDD) =
     new SchemaRDD(sqlContext, Union(logicalPlan, otherPlan.logicalPlan))
 
+  /**
+   * Performs a relational except on two SchemaRDDs
+   *
+   * @param otherPlan the [[SchemaRDD]] that should be excepted from this one.
+   *
+   * @group Query
+   */
+  def except(otherPlan: SchemaRDD): SchemaRDD =
+    new SchemaRDD(sqlContext, Except(logicalPlan, otherPlan.logicalPlan))
+
+  /**
+   * Performs a relational intersect on two SchemaRDDs
+   *
+   * @param otherPlan the [[SchemaRDD]] that should be intersected with this one.
+   *
+   * @group Query
+   */
+  def intersect(otherPlan: SchemaRDD): SchemaRDD =
+    new SchemaRDD(sqlContext, Intersect(logicalPlan, otherPlan.logicalPlan))
+
   /**
    * Filters tuples using a function over the value of the specified column.
    *

sql/core/src/test/scala/org/apache/spark/sql/DslQuerySuite.scala

@@ -168,4 +168,25 @@ class DslQuerySuite extends QueryTest {
   test("zero count") {
     assert(emptyTableData.count() === 0)
   }
+
+  test("except") {
+    checkAnswer(
+      lowerCaseData.except(upperCaseData),
+      (1, "a") ::
+      (2, "b") ::
+      (3, "c") ::
+      (4, "d") :: Nil)
+    checkAnswer(lowerCaseData.except(lowerCaseData), Nil)
+    checkAnswer(upperCaseData.except(upperCaseData), Nil)
+  }
+
+  test("intersect") {
+    checkAnswer(
+      lowerCaseData.intersect(lowerCaseData),
+      (1, "a") ::
+      (2, "b") ::
+      (3, "c") ::
+      (4, "d") :: Nil)
+    checkAnswer(lowerCaseData.intersect(upperCaseData), Nil)
+  }
 }