[SPARK-5658][SQL] Finalize DDL and write support APIs

https://issues.apache.org/jira/browse/SPARK-5658

Author: Yin Huai <yhuai@databricks.com>

This patch had conflicts when merged, resolved by
Committer: Michael Armbrust <michael@databricks.com>

Closes #4446 from yhuai/writeSupportFollowup and squashes the following commits:

f3a96f7 [Yin Huai] davies's comments.
225ff71 [Yin Huai] Use Scala TestHiveContext to initialize the Python HiveContext in Python tests.
2306f93 [Yin Huai] Style.
2091fcd [Yin Huai] Merge remote-tracking branch 'upstream/master' into writeSupportFollowup
537e28f [Yin Huai] Correctly clean up temp data.
ae4649e [Yin Huai] Fix Python test.
609129c [Yin Huai] Doc format.
92b6659 [Yin Huai] Python doc and other minor updates.
cbc717f [Yin Huai] Rename dataSourceName to source.
d1c12d3 [Yin Huai] No need to delete the duplicate rule since it has been removed in master.
22cfa70 [Yin Huai] Merge remote-tracking branch 'upstream/master' into writeSupportFollowup
d91ecb8 [Yin Huai] Fix test.
4c76d78 [Yin Huai] Simplify APIs.
3abc215 [Yin Huai] Merge remote-tracking branch 'upstream/master' into writeSupportFollowup
0832ce4 [Yin Huai] Fix test.
98e7cdb [Yin Huai] Python style.
2bf44ef [Yin Huai] Python APIs.
c204967 [Yin Huai] Format
a10223d [Yin Huai] Merge remote-tracking branch 'upstream/master' into writeSupportFollowup
9ff97d8 [Yin Huai] Add SaveMode to saveAsTable.
9b6e570 [Yin Huai] Update doc.
c2be775 [Yin Huai] Merge remote-tracking branch 'upstream/master' into writeSupportFollowup
99950a2 [Yin Huai] Use Java enum for SaveMode.
4679665 [Yin Huai] Remove duplicate rule.
77d89dc [Yin Huai] Update doc.
e04d908 [Yin Huai] Move import and add (Scala-specific) to scala APIs.
cf5703d [Yin Huai] Add checkAnswer to Java tests.
7db95ff [Yin Huai] Merge remote-tracking branch 'upstream/master' into writeSupportFollowup
6dfd386 [Yin Huai] Add java test.
f2f33ef [Yin Huai] Fix test.
e702386 [Yin Huai] Apache header.
b1e9b1b [Yin Huai] Format.
ed4e1b4 [Yin Huai] Merge remote-tracking branch 'upstream/master' into writeSupportFollowup
af9e9b3 [Yin Huai] DDL and write support API followup.
2a6213a [Yin Huai] Update API names.
e6a0b77 [Yin Huai] Update test.
43bae01 [Yin Huai] Remove createTable from HiveContext.
5ffc372 [Yin Huai] Add more load APIs to SQLContext.
5390743 [Yin Huai] Add more save APIs to DataFrame.

8 files changed, 416 insertions, 160 deletions

diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
index 2c00659496..7ae6ed6f84 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
@@ -80,18 +80,6 @@ class HiveContext(sc: SparkContext) extends SQLContext(sc) {
   }
 
   /**
-   * Creates a table using the schema of the given class.
-   *
-   * @param tableName The name of the table to create.
-   * @param allowExisting When false, an exception will be thrown if the table already exists.
-   * @tparam A A case class that is used to describe the schema of the table to be created.
-   */
-  @Deprecated
-  def createTable[A <: Product : TypeTag](tableName: String, allowExisting: Boolean = true) {
-    catalog.createTable("default", tableName, ScalaReflection.attributesFor[A], allowExisting)
-  }
-
-  /**
    * Invalidate and refresh all the cached the metadata of the given table. For performance reasons,
    * Spark SQL or the external data source library it uses might cache certain metadata about a
    * table, such as the location of blocks. When those change outside of Spark SQL, users should
@@ -107,70 +95,6 @@ class HiveContext(sc: SparkContext) extends SQLContext(sc) {
     catalog.invalidateTable("default", tableName)
   }
 
-  @Experimental
-  def createTable(tableName: String, path: String, allowExisting: Boolean): Unit = {
-    val dataSourceName = conf.defaultDataSourceName
-    createTable(tableName, dataSourceName, allowExisting, ("path", path))
-  }
-
-  @Experimental
-  def createTable(
-      tableName: String,
-      dataSourceName: String,
-      allowExisting: Boolean,
-      option: (String, String),
-      options: (String, String)*): Unit = {
-    val cmd =
-      CreateTableUsing(
-        tableName,
-        userSpecifiedSchema = None,
-        dataSourceName,
-        temporary = false,
-        (option +: options).toMap,
-        allowExisting)
-    executePlan(cmd).toRdd
-  }
-
-  @Experimental
-  def createTable(
-      tableName: String,
-      dataSourceName: String,
-      schema: StructType,
-      allowExisting: Boolean,
-      option: (String, String),
-      options: (String, String)*): Unit = {
-    val cmd =
-      CreateTableUsing(
-        tableName,
-        userSpecifiedSchema = Some(schema),
-        dataSourceName,
-        temporary = false,
-        (option +: options).toMap,
-        allowExisting)
-    executePlan(cmd).toRdd
-  }
-
-  @Experimental
-  def createTable(
-      tableName: String,
-      dataSourceName: String,
-      allowExisting: Boolean,
-      options: java.util.Map[String, String]): Unit = {
-    val opts = options.toSeq
-    createTable(tableName, dataSourceName, allowExisting, opts.head, opts.tail:_*)
-  }
-
-  @Experimental
-  def createTable(
-      tableName: String,
-      dataSourceName: String,
-      schema: StructType,
-      allowExisting: Boolean,
-      options: java.util.Map[String, String]): Unit = {
-    val opts = options.toSeq
-    createTable(tableName, dataSourceName, schema, allowExisting, opts.head, opts.tail:_*)
-  }
-
   /**
    * Analyzes the given table in the current database to generate statistics, which will be
    * used in query optimizations.
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveStrategies.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveStrategies.scala
index 95abc363ae..cb138be90e 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveStrategies.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveStrategies.scala
@@ -216,20 +216,21 @@ private[hive] trait HiveStrategies {
 
   object HiveDDLStrategy extends Strategy {
     def apply(plan: LogicalPlan): Seq[SparkPlan] = plan match {
-      case CreateTableUsing(tableName, userSpecifiedSchema, provider, false, opts, allowExisting) =>
+      case CreateTableUsing(
+      tableName, userSpecifiedSchema, provider, false, opts, allowExisting, managedIfNoPath) =>
         ExecutedCommand(
           CreateMetastoreDataSource(
-            tableName, userSpecifiedSchema, provider, opts, allowExisting)) :: Nil
+            tableName, userSpecifiedSchema, provider, opts, allowExisting, managedIfNoPath)) :: Nil
 
-      case CreateTableUsingAsSelect(tableName, provider, false, opts, allowExisting, query) =>
+      case CreateTableUsingAsSelect(tableName, provider, false, mode, opts, query) =>
         val logicalPlan = hiveContext.parseSql(query)
         val cmd =
-          CreateMetastoreDataSourceAsSelect(tableName, provider, opts, allowExisting, logicalPlan)
+          CreateMetastoreDataSourceAsSelect(tableName, provider, mode, opts, logicalPlan)
         ExecutedCommand(cmd) :: Nil
 
-      case CreateTableUsingAsLogicalPlan(tableName, provider, false, opts, allowExisting, query) =>
+      case CreateTableUsingAsLogicalPlan(tableName, provider, false, mode, opts, query) =>
         val cmd =
-          CreateMetastoreDataSourceAsSelect(tableName, provider, opts, allowExisting, query)
+          CreateMetastoreDataSourceAsSelect(tableName, provider, mode, opts, query)
         ExecutedCommand(cmd) :: Nil
 
       case _ => Nil
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/commands.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/commands.scala
index 95dcaccefd..f6bea1c6a6 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/commands.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/commands.scala
@@ -18,7 +18,9 @@
 package org.apache.spark.sql.hive.execution
 
 import org.apache.spark.annotation.DeveloperApi
-import org.apache.spark.sql.sources.ResolvedDataSource
+import org.apache.spark.sql.catalyst.analysis.EliminateAnalysisOperators
+import org.apache.spark.sql.catalyst.util._
+import org.apache.spark.sql.sources._
 import org.apache.spark.sql.{DataFrame, SQLContext}
 import org.apache.spark.sql.catalyst.expressions.Row
 import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
@@ -105,7 +107,8 @@ case class CreateMetastoreDataSource(
     userSpecifiedSchema: Option[StructType],
     provider: String,
     options: Map[String, String],
-    allowExisting: Boolean) extends RunnableCommand {
+    allowExisting: Boolean,
+    managedIfNoPath: Boolean) extends RunnableCommand {
 
   override def run(sqlContext: SQLContext): Seq[Row] = {
     val hiveContext = sqlContext.asInstanceOf[HiveContext]
@@ -120,7 +123,7 @@ case class CreateMetastoreDataSource(
 
     var isExternal = true
     val optionsWithPath =
-      if (!options.contains("path")) {
+      if (!options.contains("path") && managedIfNoPath) {
         isExternal = false
         options + ("path" -> hiveContext.catalog.hiveDefaultTableFilePath(tableName))
       } else {
@@ -141,22 +144,13 @@ case class CreateMetastoreDataSource(
 case class CreateMetastoreDataSourceAsSelect(
     tableName: String,
     provider: String,
+    mode: SaveMode,
     options: Map[String, String],
-    allowExisting: Boolean,
     query: LogicalPlan) extends RunnableCommand {
 
   override def run(sqlContext: SQLContext): Seq[Row] = {
     val hiveContext = sqlContext.asInstanceOf[HiveContext]
-
-    if (hiveContext.catalog.tableExists(tableName :: Nil)) {
-      if (allowExisting) {
-        return Seq.empty[Row]
-      } else {
-        sys.error(s"Table $tableName already exists.")
-      }
-    }
-
-    val df = DataFrame(hiveContext, query)
+    var createMetastoreTable = false
     var isExternal = true
     val optionsWithPath =
       if (!options.contains("path")) {
@@ -166,15 +160,82 @@ case class CreateMetastoreDataSourceAsSelect(
         options
       }
 
-    // Create the relation based on the data of df.
-    ResolvedDataSource(sqlContext, provider, optionsWithPath, df)
+    if (sqlContext.catalog.tableExists(Seq(tableName))) {
+      // Check if we need to throw an exception or just return.
+      mode match {
+        case SaveMode.ErrorIfExists =>
+          sys.error(s"Table $tableName already exists. " +
+            s"If you want to append into it, please set mode to SaveMode.Append. " +
+            s"Or, if you want to overwrite it, please set mode to SaveMode.Overwrite.")
+        case SaveMode.Ignore =>
+          // Since the table already exists and the save mode is Ignore, we will just return.
+          return Seq.empty[Row]
+        case SaveMode.Append =>
+          // Check if the specified data source match the data source of the existing table.
+          val resolved =
+            ResolvedDataSource(sqlContext, Some(query.schema), provider, optionsWithPath)
+          val createdRelation = LogicalRelation(resolved.relation)
+          EliminateAnalysisOperators(sqlContext.table(tableName).logicalPlan) match {
+            case l @ LogicalRelation(i: InsertableRelation) =>
+              if (l.schema != createdRelation.schema) {
+                val errorDescription =
+                  s"Cannot append to table $tableName because the schema of this " +
+                    s"DataFrame does not match the schema of table $tableName."
+                val errorMessage =
+                  s"""
+                |$errorDescription
+                |== Schemas ==
+                |${sideBySide(
+                s"== Expected Schema ==" +:
+                  l.schema.treeString.split("\\\n"),
+                s"== Actual Schema ==" +:
+                  createdRelation.schema.treeString.split("\\\n")).mkString("\n")}
+              """.stripMargin
+                sys.error(errorMessage)
+              } else if (i != createdRelation.relation) {
+                val errorDescription =
+                  s"Cannot append to table $tableName because the resolved relation does not " +
+                  s"match the existing relation of $tableName. " +
+                  s"You can use insertInto($tableName, false) to append this DataFrame to the " +
+                  s"table $tableName and using its data source and options."
+                val errorMessage =
+                  s"""
+                |$errorDescription
+                |== Relations ==
+                |${sideBySide(
+                s"== Expected Relation ==" ::
+                  l.toString :: Nil,
+                s"== Actual Relation ==" ::
+                  createdRelation.toString :: Nil).mkString("\n")}
+              """.stripMargin
+                sys.error(errorMessage)
+              }
+            case o =>
+              sys.error(s"Saving data in ${o.toString} is not supported.")
+          }
+        case SaveMode.Overwrite =>
+          hiveContext.sql(s"DROP TABLE IF EXISTS $tableName")
+          // Need to create the table again.
+          createMetastoreTable = true
+      }
+    } else {
+      // The table does not exist. We need to create it in metastore.
+      createMetastoreTable = true
+    }
 
-    hiveContext.catalog.createDataSourceTable(
-      tableName,
-      None,
-      provider,
-      optionsWithPath,
-      isExternal)
+    val df = DataFrame(hiveContext, query)
+
+    // Create the relation based on the data of df.
+    ResolvedDataSource(sqlContext, provider, mode, optionsWithPath, df)
+
+    if (createMetastoreTable) {
+      hiveContext.catalog.createDataSourceTable(
+        tableName,
+        Some(df.schema),
+        provider,
+        optionsWithPath,
+        isExternal)
+    }
 
     Seq.empty[Row]
   }
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/TestHive.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/test/TestHive.scala
index 7c1d1133c3..840fbc1972 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/TestHive.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/test/TestHive.scala
@@ -20,9 +20,6 @@ package org.apache.spark.sql.hive.test
 import java.io.File
 import java.util.{Set => JavaSet}
 
-import scala.collection.mutable
-import scala.language.implicitConversions
-
 import org.apache.hadoop.hive.ql.exec.FunctionRegistry
 import org.apache.hadoop.hive.ql.io.avro.{AvroContainerInputFormat, AvroContainerOutputFormat}
 import org.apache.hadoop.hive.ql.metadata.Table
@@ -30,16 +27,18 @@ import org.apache.hadoop.hive.ql.processors._
 import org.apache.hadoop.hive.serde2.RegexSerDe
 import org.apache.hadoop.hive.serde2.`lazy`.LazySimpleSerDe
 import org.apache.hadoop.hive.serde2.avro.AvroSerDe
-
-import org.apache.spark.{SparkConf, SparkContext}
-import org.apache.spark.util.Utils
+import org.apache.spark.sql.SQLConf
 import org.apache.spark.sql.catalyst.analysis._
 import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
 import org.apache.spark.sql.catalyst.util._
 import org.apache.spark.sql.execution.CacheTableCommand
 import org.apache.spark.sql.hive._
-import org.apache.spark.sql.SQLConf
 import org.apache.spark.sql.hive.execution.HiveNativeCommand
+import org.apache.spark.util.Utils
+import org.apache.spark.{SparkConf, SparkContext}
+
+import scala.collection.mutable
+import scala.language.implicitConversions
 
 /* Implicit conversions */
 import scala.collection.JavaConversions._
@@ -224,11 +223,10 @@ class TestHiveContext(sc: SparkContext) extends HiveContext(sc) {
       }
     }),
     TestTable("src_thrift", () => {
-      import org.apache.thrift.protocol.TBinaryProtocol
-      import org.apache.hadoop.hive.serde2.thrift.test.Complex
       import org.apache.hadoop.hive.serde2.thrift.ThriftDeserializer
-      import org.apache.hadoop.mapred.SequenceFileInputFormat
-      import org.apache.hadoop.mapred.SequenceFileOutputFormat
+      import org.apache.hadoop.hive.serde2.thrift.test.Complex
+      import org.apache.hadoop.mapred.{SequenceFileInputFormat, SequenceFileOutputFormat}
+      import org.apache.thrift.protocol.TBinaryProtocol
 
       val srcThrift = new Table("default", "src_thrift")
       srcThrift.setFields(Nil)
diff --git a/sql/hive/src/test/java/org/apache/spark/sql/hive/JavaMetastoreDataSourcesSuite.java b/sql/hive/src/test/java/org/apache/spark/sql/hive/JavaMetastoreDataSourcesSuite.java
new file mode 100644
index 0000000000..9744a2aa3f
--- /dev/null
+++ b/sql/hive/src/test/java/org/apache/spark/sql/hive/JavaMetastoreDataSourcesSuite.java
@@ -0,0 +1,147 @@
+/*
+ * 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.hive;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.spark.sql.sources.SaveMode;
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import org.apache.spark.api.java.JavaRDD;
+import org.apache.spark.api.java.JavaSparkContext;
+import org.apache.spark.sql.DataFrame;
+import org.apache.spark.sql.QueryTest$;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.hive.test.TestHive$;
+import org.apache.spark.sql.types.DataTypes;
+import org.apache.spark.sql.types.StructField;
+import org.apache.spark.sql.types.StructType;
+import org.apache.spark.util.Utils;
+
+public class JavaMetastoreDataSourcesSuite {
+  private transient JavaSparkContext sc;
+  private transient HiveContext sqlContext;
+
+  String originalDefaultSource;
+  File path;
+  Path hiveManagedPath;
+  FileSystem fs;
+  DataFrame df;
+
+  private void checkAnswer(DataFrame actual, List<Row> expected) {
+    String errorMessage = QueryTest$.MODULE$.checkAnswer(actual, expected);
+    if (errorMessage != null) {
+      Assert.fail(errorMessage);
+    }
+  }
+
+  @Before
+  public void setUp() throws IOException {
+    sqlContext = TestHive$.MODULE$;
+    sc = new JavaSparkContext(sqlContext.sparkContext());
+
+    originalDefaultSource = sqlContext.conf().defaultDataSourceName();
+    path =
+      Utils.createTempDir(System.getProperty("java.io.tmpdir"), "datasource").getCanonicalFile();
+    if (path.exists()) {
+      path.delete();
+    }
+    hiveManagedPath = new Path(sqlContext.catalog().hiveDefaultTableFilePath("javaSavedTable"));
+    fs = hiveManagedPath.getFileSystem(sc.hadoopConfiguration());
+    if (fs.exists(hiveManagedPath)){
+      fs.delete(hiveManagedPath, true);
+    }
+
+    List<String> jsonObjects = new ArrayList<String>(10);
+    for (int i = 0; i < 10; i++) {
+      jsonObjects.add("{\"a\":" + i + ", \"b\":\"str" + i + "\"}");
+    }
+    JavaRDD<String> rdd = sc.parallelize(jsonObjects);
+    df = sqlContext.jsonRDD(rdd);
+    df.registerTempTable("jsonTable");
+  }
+
+  @After
+  public void tearDown() throws IOException {
+    // Clean up tables.
+    sqlContext.sql("DROP TABLE IF EXISTS javaSavedTable");
+    sqlContext.sql("DROP TABLE IF EXISTS externalTable");
+  }
+
+  @Test
+  public void saveExternalTableAndQueryIt() {
+    Map<String, String> options = new HashMap<String, String>();
+    options.put("path", path.toString());
+    df.saveAsTable("javaSavedTable", "org.apache.spark.sql.json", SaveMode.Append, options);
+
+    checkAnswer(
+      sqlContext.sql("SELECT * FROM javaSavedTable"),
+      df.collectAsList());
+
+    DataFrame loadedDF =
+      sqlContext.createExternalTable("externalTable", "org.apache.spark.sql.json", options);
+
+    checkAnswer(loadedDF, df.collectAsList());
+    checkAnswer(
+      sqlContext.sql("SELECT * FROM externalTable"),
+      df.collectAsList());
+  }
+
+  @Test
+  public void saveExternalTableWithSchemaAndQueryIt() {
+    Map<String, String> options = new HashMap<String, String>();
+    options.put("path", path.toString());
+    df.saveAsTable("javaSavedTable", "org.apache.spark.sql.json", SaveMode.Append, options);
+
+    checkAnswer(
+      sqlContext.sql("SELECT * FROM javaSavedTable"),
+      df.collectAsList());
+
+    List<StructField> fields = new ArrayList<>();
+    fields.add(DataTypes.createStructField("b", DataTypes.StringType, true));
+    StructType schema = DataTypes.createStructType(fields);
+    DataFrame loadedDF =
+      sqlContext.createExternalTable("externalTable", "org.apache.spark.sql.json", schema, options);
+
+    checkAnswer(
+      loadedDF,
+      sqlContext.sql("SELECT b FROM javaSavedTable").collectAsList());
+    checkAnswer(
+      sqlContext.sql("SELECT * FROM externalTable"),
+      sqlContext.sql("SELECT b FROM javaSavedTable").collectAsList());
+  }
+
+  @Test
+  public void saveTableAndQueryIt() {
+    Map<String, String> options = new HashMap<String, String>();
+    df.saveAsTable("javaSavedTable", "org.apache.spark.sql.json", SaveMode.Append, options);
+
+    checkAnswer(
+      sqlContext.sql("SELECT * FROM javaSavedTable"),
+      df.collectAsList());
+  }
+}
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/QueryTest.scala b/sql/hive/src/test/scala/org/apache/spark/sql/QueryTest.scala
index ba39129388..0270e63557 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/QueryTest.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/QueryTest.scala
@@ -17,10 +17,8 @@
 
 package org.apache.spark.sql
 
-import org.scalatest.FunSuite
+import scala.collection.JavaConversions._
 
-import org.apache.spark.sql.catalyst.expressions.{ExprId, AttributeReference}
-import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
 import org.apache.spark.sql.catalyst.plans._
 import org.apache.spark.sql.catalyst.util._
 
@@ -55,9 +53,36 @@ class QueryTest extends PlanTest {
   /**
    * Runs the plan and makes sure the answer matches the expected result.
    * @param rdd the [[DataFrame]] to be executed
-   * @param expectedAnswer the expected result, can either be an Any, Seq[Product], or Seq[ Seq[Any] ].
+   * @param expectedAnswer the expected result in a [[Seq]] of [[Row]]s.
    */
   protected def checkAnswer(rdd: DataFrame, expectedAnswer: Seq[Row]): Unit = {
+    QueryTest.checkAnswer(rdd, expectedAnswer) match {
+      case Some(errorMessage) => fail(errorMessage)
+      case None =>
+    }
+  }
+
+  protected def checkAnswer(rdd: DataFrame, expectedAnswer: Row): Unit = {
+    checkAnswer(rdd, Seq(expectedAnswer))
+  }
+
+  def sqlTest(sqlString: String, expectedAnswer: Seq[Row])(implicit sqlContext: SQLContext): Unit = {
+    test(sqlString) {
+      checkAnswer(sqlContext.sql(sqlString), expectedAnswer)
+    }
+  }
+}
+
+object QueryTest {
+  /**
+   * Runs the plan and makes sure the answer matches the expected result.
+   * If there was exception during the execution or the contents of the DataFrame does not
+   * match the expected result, an error message will be returned. Otherwise, a [[None]] will
+   * be returned.
+   * @param rdd the [[DataFrame]] to be executed
+   * @param expectedAnswer the expected result in a [[Seq]] of [[Row]]s.
+   */
+  def checkAnswer(rdd: DataFrame, expectedAnswer: Seq[Row]): Option[String] = {
     val isSorted = rdd.logicalPlan.collect { case s: logical.Sort => s }.nonEmpty
     def prepareAnswer(answer: Seq[Row]): Seq[Row] = {
       // Converts data to types that we can do equality comparison using Scala collections.
@@ -73,18 +98,20 @@ class QueryTest extends PlanTest {
     }
     val sparkAnswer = try rdd.collect().toSeq catch {
       case e: Exception =>
-        fail(
+        val errorMessage =
           s"""
             |Exception thrown while executing query:
             |${rdd.queryExecution}
             |== Exception ==
             |$e
             |${org.apache.spark.sql.catalyst.util.stackTraceToString(e)}
-          """.stripMargin)
+          """.stripMargin
+        return Some(errorMessage)
     }
 
     if (prepareAnswer(expectedAnswer) != prepareAnswer(sparkAnswer)) {
-      fail(s"""
+      val errorMessage =
+        s"""
         |Results do not match for query:
         |${rdd.logicalPlan}
         |== Analyzed Plan ==
@@ -93,22 +120,21 @@ class QueryTest extends PlanTest {
         |${rdd.queryExecution.executedPlan}
         |== Results ==
         |${sideBySide(
-        s"== Correct Answer - ${expectedAnswer.size} ==" +:
-          prepareAnswer(expectedAnswer).map(_.toString),
-        s"== Spark Answer - ${sparkAnswer.size} ==" +:
-          prepareAnswer(sparkAnswer).map(_.toString)).mkString("\n")}
-      """.stripMargin)
+          s"== Correct Answer - ${expectedAnswer.size} ==" +:
+            prepareAnswer(expectedAnswer).map(_.toString),
+          s"== Spark Answer - ${sparkAnswer.size} ==" +:
+            prepareAnswer(sparkAnswer).map(_.toString)).mkString("\n")}
+      """.stripMargin
+      return Some(errorMessage)
     }
-  }
 
-  protected def checkAnswer(rdd: DataFrame, expectedAnswer: Row): Unit = {
-    checkAnswer(rdd, Seq(expectedAnswer))
+    return None
   }
 
-  def sqlTest(sqlString: String, expectedAnswer: Seq[Row])(implicit sqlContext: SQLContext): Unit = {
-    test(sqlString) {
-      checkAnswer(sqlContext.sql(sqlString), expectedAnswer)
+  def checkAnswer(rdd: DataFrame, expectedAnswer: java.util.List[Row]): String = {
+    checkAnswer(rdd, expectedAnswer.toSeq) match {
+      case Some(errorMessage) => errorMessage
+      case None => null
     }
   }
-
 }
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/InsertIntoHiveTableSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/InsertIntoHiveTableSuite.scala
index 869d01eb39..43da7519ac 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/InsertIntoHiveTableSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/InsertIntoHiveTableSuite.scala
@@ -19,7 +19,11 @@ package org.apache.spark.sql.hive
 
 import java.io.File
 
+import org.scalatest.BeforeAndAfter
+
 import com.google.common.io.Files
+
+import org.apache.spark.sql.execution.QueryExecutionException
 import org.apache.spark.sql.{QueryTest, _}
 import org.apache.spark.sql.hive.test.TestHive
 import org.apache.spark.sql.types._
@@ -29,15 +33,22 @@ import org.apache.spark.sql.hive.test.TestHive._
 
 case class TestData(key: Int, value: String)
 
-class InsertIntoHiveTableSuite extends QueryTest {
+class InsertIntoHiveTableSuite extends QueryTest with BeforeAndAfter {
   import org.apache.spark.sql.hive.test.TestHive.implicits._
 
   val testData = TestHive.sparkContext.parallelize(
     (1 to 100).map(i => TestData(i, i.toString)))
-  testData.registerTempTable("testData")
+
+  before {
+    // Since every we are doing tests for DDL statements,
+    // it is better to reset before every test.
+    TestHive.reset()
+    // Register the testData, which will be used in every test.
+    testData.registerTempTable("testData")
+  }
 
   test("insertInto() HiveTable") {
-    createTable[TestData]("createAndInsertTest")
+    sql("CREATE TABLE createAndInsertTest (key int, value string)")
 
     // Add some data.
     testData.insertInto("createAndInsertTest")
@@ -68,16 +79,18 @@ class InsertIntoHiveTableSuite extends QueryTest {
   }
 
   test("Double create fails when allowExisting = false") {
-    createTable[TestData]("doubleCreateAndInsertTest")
+    sql("CREATE TABLE doubleCreateAndInsertTest (key int, value string)")
 
-    intercept[org.apache.hadoop.hive.ql.metadata.HiveException] {
-      createTable[TestData]("doubleCreateAndInsertTest", allowExisting = false)
-    }
+    val message = intercept[QueryExecutionException] {
+      sql("CREATE TABLE doubleCreateAndInsertTest (key int, value string)")
+    }.getMessage
+
+    println("message!!!!" + message)
   }
 
   test("Double create does not fail when allowExisting = true") {
-    createTable[TestData]("createAndInsertTest")
-    createTable[TestData]("createAndInsertTest")
+    sql("CREATE TABLE doubleCreateAndInsertTest (key int, value string)")
+    sql("CREATE TABLE IF NOT EXISTS doubleCreateAndInsertTest (key int, value string)")
   }
 
   test("SPARK-4052: scala.collection.Map as value type of MapType") {
@@ -98,7 +111,7 @@ class InsertIntoHiveTableSuite extends QueryTest {
   }
 
   test("SPARK-4203:random partition directory order") {
-    createTable[TestData]("tmp_table")
+    sql("CREATE TABLE tmp_table (key int, value string)")
     val tmpDir = Files.createTempDir()
     sql(s"CREATE TABLE table_with_partition(c1 string) PARTITIONED by (p1 string,p2 string,p3 string,p4 string,p5 string) location '${tmpDir.toURI.toString}'  ")
     sql("INSERT OVERWRITE TABLE table_with_partition  partition (p1='a',p2='b',p3='c',p4='c',p5='1') SELECT 'blarr' FROM tmp_table")
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/MetastoreDataSourcesSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/MetastoreDataSourcesSuite.scala
index 9ce058909f..f94aabd29a 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/MetastoreDataSourcesSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/MetastoreDataSourcesSuite.scala
@@ -19,10 +19,12 @@ package org.apache.spark.sql.hive
 
 import java.io.File
 
+import org.apache.spark.sql.sources.SaveMode
 import org.scalatest.BeforeAndAfterEach
 
 import org.apache.commons.io.FileUtils
 import org.apache.hadoop.fs.Path
+import org.apache.hadoop.mapred.InvalidInputException
 
 import org.apache.spark.sql.catalyst.util
 import org.apache.spark.sql._
@@ -41,11 +43,11 @@ class MetastoreDataSourcesSuite extends QueryTest with BeforeAndAfterEach {
 
   override def afterEach(): Unit = {
     reset()
-    if (ctasPath.exists()) Utils.deleteRecursively(ctasPath)
+    if (tempPath.exists()) Utils.deleteRecursively(tempPath)
   }
 
   val filePath = Utils.getSparkClassLoader.getResource("sample.json").getFile
-  var ctasPath: File = util.getTempFilePath("jsonCTAS").getCanonicalFile
+  var tempPath: File = util.getTempFilePath("jsonCTAS").getCanonicalFile
 
   test ("persistent JSON table") {
     sql(
@@ -270,7 +272,7 @@ class MetastoreDataSourcesSuite extends QueryTest with BeforeAndAfterEach {
         |CREATE TABLE ctasJsonTable
         |USING org.apache.spark.sql.json.DefaultSource
         |OPTIONS (
-        |  path '${ctasPath}'
+        |  path '${tempPath}'
         |) AS
         |SELECT * FROM jsonTable
       """.stripMargin)
@@ -297,7 +299,7 @@ class MetastoreDataSourcesSuite extends QueryTest with BeforeAndAfterEach {
         |CREATE TABLE ctasJsonTable
         |USING org.apache.spark.sql.json.DefaultSource
         |OPTIONS (
-        |  path '${ctasPath}'
+        |  path '${tempPath}'
         |) AS
         |SELECT * FROM jsonTable
       """.stripMargin)
@@ -309,7 +311,7 @@ class MetastoreDataSourcesSuite extends QueryTest with BeforeAndAfterEach {
         |CREATE TABLE ctasJsonTable
         |USING org.apache.spark.sql.json.DefaultSource
         |OPTIONS (
-        |  path '${ctasPath}'
+        |  path '${tempPath}'
         |) AS
         |SELECT * FROM jsonTable
       """.stripMargin)
@@ -325,7 +327,7 @@ class MetastoreDataSourcesSuite extends QueryTest with BeforeAndAfterEach {
         |CREATE TABLE IF NOT EXISTS ctasJsonTable
         |USING org.apache.spark.sql.json.DefaultSource
         |OPTIONS (
-        |  path '${ctasPath}'
+        |  path '${tempPath}'
         |) AS
         |SELECT a FROM jsonTable
       """.stripMargin)
@@ -400,38 +402,122 @@ class MetastoreDataSourcesSuite extends QueryTest with BeforeAndAfterEach {
     sql("DROP TABLE jsonTable").collect().foreach(println)
   }
 
-  test("save and load table") {
+  test("save table") {
     val originalDefaultSource = conf.defaultDataSourceName
-    conf.setConf("spark.sql.default.datasource", "org.apache.spark.sql.json")
 
     val rdd = sparkContext.parallelize((1 to 10).map(i => s"""{"a":$i, "b":"str${i}"}"""))
     val df = jsonRDD(rdd)
 
+    conf.setConf(SQLConf.DEFAULT_DATA_SOURCE_NAME, "org.apache.spark.sql.json")
+    // Save the df as a managed table (by not specifiying the path).
     df.saveAsTable("savedJsonTable")
 
     checkAnswer(
       sql("SELECT * FROM savedJsonTable"),
       df.collect())
 
-    createTable("createdJsonTable", catalog.hiveDefaultTableFilePath("savedJsonTable"), false)
+    // Right now, we cannot append to an existing JSON table.
+    intercept[RuntimeException] {
+      df.saveAsTable("savedJsonTable", SaveMode.Append)
+    }
+
+    // We can overwrite it.
+    df.saveAsTable("savedJsonTable", SaveMode.Overwrite)
+    checkAnswer(
+      sql("SELECT * FROM savedJsonTable"),
+      df.collect())
+
+    // When the save mode is Ignore, we will do nothing when the table already exists.
+    df.select("b").saveAsTable("savedJsonTable", SaveMode.Ignore)
+    assert(df.schema === table("savedJsonTable").schema)
+    checkAnswer(
+      sql("SELECT * FROM savedJsonTable"),
+      df.collect())
+
+    // Drop table will also delete the data.
+    sql("DROP TABLE savedJsonTable")
+    intercept[InvalidInputException] {
+      jsonFile(catalog.hiveDefaultTableFilePath("savedJsonTable"))
+    }
+
+    // Create an external table by specifying the path.
+    conf.setConf(SQLConf.DEFAULT_DATA_SOURCE_NAME, "not a source name")
+    df.saveAsTable(
+      "savedJsonTable",
+      "org.apache.spark.sql.json",
+      SaveMode.Append,
+      Map("path" -> tempPath.toString))
+    checkAnswer(
+      sql("SELECT * FROM savedJsonTable"),
+      df.collect())
+
+    // Data should not be deleted after we drop the table.
+    sql("DROP TABLE savedJsonTable")
+    checkAnswer(
+      jsonFile(tempPath.toString),
+      df.collect())
+
+    conf.setConf(SQLConf.DEFAULT_DATA_SOURCE_NAME, originalDefaultSource)
+  }
+
+  test("create external table") {
+    val originalDefaultSource = conf.defaultDataSourceName
+
+    val rdd = sparkContext.parallelize((1 to 10).map(i => s"""{"a":$i, "b":"str${i}"}"""))
+    val df = jsonRDD(rdd)
+
+    conf.setConf(SQLConf.DEFAULT_DATA_SOURCE_NAME, "not a source name")
+    df.saveAsTable(
+      "savedJsonTable",
+      "org.apache.spark.sql.json",
+      SaveMode.Append,
+      Map("path" -> tempPath.toString))
+
+    conf.setConf(SQLConf.DEFAULT_DATA_SOURCE_NAME, "org.apache.spark.sql.json")
+    createExternalTable("createdJsonTable", tempPath.toString)
     assert(table("createdJsonTable").schema === df.schema)
     checkAnswer(
       sql("SELECT * FROM createdJsonTable"),
       df.collect())
 
-    val message = intercept[RuntimeException] {
-      createTable("createdJsonTable", filePath.toString, false)
+    var message = intercept[RuntimeException] {
+      createExternalTable("createdJsonTable", filePath.toString)
     }.getMessage
     assert(message.contains("Table createdJsonTable already exists."),
       "We should complain that ctasJsonTable already exists")
 
-    createTable("createdJsonTable", filePath.toString, true)
-    // createdJsonTable should be not changed.
-    assert(table("createdJsonTable").schema === df.schema)
+    // Data should not be deleted.
+    sql("DROP TABLE createdJsonTable")
     checkAnswer(
-      sql("SELECT * FROM createdJsonTable"),
+      jsonFile(tempPath.toString),
       df.collect())
 
-    conf.setConf("spark.sql.default.datasource", originalDefaultSource)
+    // Try to specify the schema.
+    conf.setConf(SQLConf.DEFAULT_DATA_SOURCE_NAME, "not a source name")
+    val schema = StructType(StructField("b", StringType, true) :: Nil)
+    createExternalTable(
+      "createdJsonTable",
+      "org.apache.spark.sql.json",
+      schema,
+      Map("path" -> tempPath.toString))
+    checkAnswer(
+      sql("SELECT * FROM createdJsonTable"),
+      sql("SELECT b FROM savedJsonTable").collect())
+
+    sql("DROP TABLE createdJsonTable")
+
+    message = intercept[RuntimeException] {
+      createExternalTable(
+        "createdJsonTable",
+        "org.apache.spark.sql.json",
+        schema,
+        Map.empty[String, String])
+    }.getMessage
+    assert(
+      message.contains("Option 'path' not specified"),
+      "We should complain that path is not specified.")
+
+    sql("DROP TABLE savedJsonTable")
+    conf.setConf(SQLConf.DEFAULT_DATA_SOURCE_NAME, originalDefaultSource)
   }
 }