Made output of "EXPLAIN" play well with JDBC output format

Author: liancheng

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

@@ -83,8 +83,8 @@ case class ExplainCommand(
   override protected[sql] lazy val sideEffectResult: Seq[String] = this.toString.split("\n")
 
   def execute(): RDD[Row] = {
-    val explanation = sideEffectResult.mkString("\n")
-    context.sparkContext.parallelize(Seq(new GenericRow(Array[Any](explanation))), 1)
+    val explanation = sideEffectResult.map(row => new GenericRow(Array[Any](row)))
+    context.sparkContext.parallelize(explanation, 1)
   }
 
   override def otherCopyArgs = context :: Nil

sql/hive/src/test/scala/org/apache/spark/sql/hive/api/java/JavaHiveQLSuite.scala

@@ -49,7 +49,7 @@ class JavaHiveQLSuite extends FunSuite {
 
   def isExplanation(result: JavaSchemaRDD) = {
     val explanation = result.collect().map(_.getString(0))
-    explanation.size == 1 && explanation.head.startsWith(explainCommandClassName)
+    explanation.size > 1 && explanation.head.startsWith(explainCommandClassName)
   }
 
   ignore("Query Hive native command execution result") {

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveQuerySuite.scala

@@ -169,7 +169,7 @@ class HiveQuerySuite extends HiveComparisonTest {
 
   def isExplanation(result: SchemaRDD) = {
     val explanation = result.select('plan).collect().map { case Row(plan: String) => plan }
-    explanation.size == 1 && explanation.head.startsWith(explainCommandClassName)
+    explanation.size > 1 && explanation.head.startsWith(explainCommandClassName)
   }
 
   test("SPARK-1704: Explain commands as a SchemaRDD") {