address review comments

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

@@ -216,7 +216,7 @@ private[hive] object HiveQl {
    */
   def getAst(sql: String): ASTNode = {
     /*
-     * Context has to be passed in in hive0.13.1.
+     * Context has to be passed in hive0.13.1.
      * Otherwise, there will be Null pointer exception,
      * when retrieving properties form HiveConf.
      */

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

@@ -61,6 +61,7 @@ class TestHiveContext(sc: SparkContext) extends HiveContext(sc) {
   // By clearing the port we force Spark to pick a new one.  This allows us to rerun tests
   // without restarting the JVM.
   System.clearProperty("spark.hostPort")
+  CommandProcessorFactory.clean(hiveconf)
 
   lazy val warehousePath = getTempFilePath("sparkHiveWarehouse").getCanonicalPath
   lazy val metastorePath = getTempFilePath("sparkHiveMetastore").getCanonicalPath
@@ -79,7 +80,6 @@ class TestHiveContext(sc: SparkContext) extends HiveContext(sc) {
   // For some hive test case which contain ${system:test.tmp.dir}
   System.setProperty("test.tmp.dir", testTempDir.getCanonicalPath)
 
-  CommandProcessorFactory.clean(hiveconf)
   configure() // Must be called before initializing the catalog below.
 
   /** The location of the compiled hive distribution */
@@ -371,6 +371,8 @@ class TestHiveContext(sc: SparkContext) extends HiveContext(sc) {
    * tests.
    */
   protected val originalUdfs: JavaSet[String] = FunctionRegistry.getFunctionNames
+
+  // Database default may not exist in 0.13.1, create it if not exist
   HiveShim.createDefaultDBIfNeeded(this)
 
   /**

sql/hive/src/test/scala/org/apache/spark/sql/hive/StatisticsSuite.scala

@@ -81,7 +81,7 @@ class StatisticsSuite extends QueryTest with BeforeAndAfterAll {
     sql("INSERT INTO TABLE analyzeTable SELECT * FROM src").collect()
     sql("INSERT INTO TABLE analyzeTable SELECT * FROM src").collect()
 
-    // TODO: How it works? needs to add it back for other hive version.
+    // TODO: How does it works? needs to add it back for other hive version.
     if (HiveShim.version =="0.12.0") {
       assert(queryTotalSize("analyzeTable") === defaultSizeInBytes)
     }

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

@@ -557,7 +557,8 @@ class HiveQuerySuite extends HiveComparisonTest {
           |WITH serdeproperties('s1'='9')
         """.stripMargin)
     }
-    // now only verify 0.12.0, and ignore other versions due to binary compatability
+    // Now only verify 0.12.0, and ignore other versions due to binary compatability
+    // current TestSerDe.jar is from 0.12.0
     if (HiveShim.version == "0.12.0") {
       sql(s"ADD JAR $testJar")
       sql(

sql/hive/v0.12.0/src/main/scala/org/apache/spark/sql/hive/Shim.scala

@@ -69,7 +69,7 @@ private[hive] object HiveShim {
     ColumnProjectionUtils.appendReadColumnNames(conf, names)
   }
 
-  def getExternalTmpPath(context: Context, uri: URI): String = {
+  def getExternalTmpPath(context: Context, uri: URI) = {
     context.getExternalTmpFileURI(uri)
   }
 

sql/hive/v0.13.1/src/main/scala/org/apache/spark/sql/hive/Shim.scala

@@ -40,10 +40,10 @@ import scala.language.implicitConversions
 private[hive] object HiveShim {
   val version = "0.13.1"
   /*
-   * TODO: hive-0.13 support DECIMAL(precision, scale), DECIMAL in hive-0.12 is actually DECIMAL(10,0)
+   * TODO: hive-0.13 support DECIMAL(precision, scale), DECIMAL in hive-0.12 is actually DECIMAL(38,unbounded)
    * Full support of new decimal feature need to be fixed in seperate PR.
    */
-  val metastoreDecimal = "decimal(10,0)"
+  val metastoreDecimal = "decimal\\((\\d+),(\\d+)\\)".r
 
   def getTableDesc(
     serdeClass: Class[_ <: Deserializer],
@@ -82,8 +82,7 @@ private[hive] object HiveShim {
     for (col <- cols) {
       if (first) {
         first = false
-      }
-      else {
+      } else {
         result.append(',')
       }
       result.append(col)
@@ -98,7 +97,9 @@ private[hive] object HiveShim {
     if (ids != null && ids.size > 0) {
       ColumnProjectionUtils.appendReadColumns(conf, ids)
     }
-    appendReadColumnNames(conf, names)
+    if (names == null && names.size > 0) {
+      appendReadColumnNames(conf, names)
+    }
   }
 
   def getExternalTmpPath(context: Context, path: Path) = {
@@ -110,17 +111,16 @@ private[hive] object HiveShim {
   def getAllPartitionsOf(client: Hive, tbl: Table) =  client.getAllPartitionsOf(tbl)
 
   /*
-   * Bug introdiced in hive-0.13. FileSinkDesc is serilizable, but its member path is not.
+   * Bug introdiced in hive-0.13. FileSinkDesc is serializable, but its member path is not.
    * Fix it through wrapper.
    * */
   implicit def wrapperToFileSinkDesc(w: ShimFileSinkDesc): FileSinkDesc = {
-        var f = new FileSinkDesc(new Path(w.dir), w.tableInfo, w.compressed)
-        f.setCompressed(w.compressed)
-        f.setCompressCodec(w.compressCodec)
-        f.setCompressType(w.compressType)
-        f.setTableInfo(w.tableInfo)
-        f.setDestTableId(w.destTableId)
-        f
+    var f = new FileSinkDesc(new Path(w.dir), w.tableInfo, w.compressed)
+    f.setCompressCodec(w.compressCodec)
+    f.setCompressType(w.compressType)
+    f.setTableInfo(w.tableInfo)
+    f.setDestTableId(w.destTableId)
+    f
   }
 }