modify HiveStrategies to adapt DescribeCommand interface

Author: Yanbo Liang

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

@@ -172,11 +172,11 @@ case class UncacheTableCommand(tableName: String) extends RunnableCommand {
  */
 @DeveloperApi
 case class DescribeCommand(
-    logicalPlan: LogicalPlan,
+    table: LogicalPlan,
     isExtended: Boolean) extends RunnableCommand {
 
   override def run(sqlContext: SQLContext) = {
-    val plan = sqlContext.executePlan(logicalPlan).analyzed
+    val plan = sqlContext.executePlan(table).analyzed
     plan.output.map(field => Row(field.name, field.dataType.toString, null))
   }
 

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

@@ -229,7 +229,7 @@ private[hive] trait HiveStrategies {
             ExecutedCommand(
               DescribeHiveTableCommand(t, describe.output, describe.isExtended)) :: Nil
           case o: LogicalPlan =>
-            ExecutedCommand(RunnableDescribeCommand(planLater(o), describe.output)) :: Nil
+            ExecutedCommand(RunnableDescribeCommand(o, describe.isExtended)) :: Nil
         }
 
       case _ => Nil