[SPARK-14145][SQL] Remove the untyped version of Dataset.groupByKey

## What changes were proposed in this pull request?
Dataset has two variants of groupByKey, one for untyped and the other for typed. It actually doesn't make as much sense to have an untyped API here, since apps that want to use untyped APIs should just use the groupBy "DataFrame" API.

## How was this patch tested?
This patch removes a method, and removes the associated tests.

Author: Reynold Xin <rxin@databricks.com>

Closes #11949 from rxin/SPARK-14145.

4 files changed, 1 insertions, 99 deletions

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala b/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
index ec0b3c78ed..703ea4d149 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
@@ -1180,32 +1180,6 @@ class Dataset[T] private[sql](
 
   /**
    * :: Experimental ::
-   * Returns a [[KeyValueGroupedDataset]] where the data is grouped by the given [[Column]]
-   * expressions.
-   *
-   * @group typedrel
-   * @since 2.0.0
-   */
-  @Experimental
-  @scala.annotation.varargs
-  def groupByKey(cols: Column*): KeyValueGroupedDataset[Row, T] = {
-    val withKeyColumns = logicalPlan.output ++ cols.map(_.expr).map(UnresolvedAlias(_))
-    val withKey = Project(withKeyColumns, logicalPlan)
-    val executed = sqlContext.executePlan(withKey)
-
-    val dataAttributes = executed.analyzed.output.dropRight(cols.size)
-    val keyAttributes = executed.analyzed.output.takeRight(cols.size)
-
-    new KeyValueGroupedDataset(
-      RowEncoder(keyAttributes.toStructType),
-      encoderFor[T],
-      executed,
-      dataAttributes,
-      keyAttributes)
-  }
-
-  /**
-   * :: Experimental ::
    * (Java-specific)
    * Returns a [[KeyValueGroupedDataset]] where the data is grouped by the given key `func`.
    *
diff --git a/sql/core/src/test/java/test/org/apache/spark/sql/JavaDatasetSuite.java b/sql/core/src/test/java/test/org/apache/spark/sql/JavaDatasetSuite.java
index 18f17a85a9..86db8df4c0 100644
--- a/sql/core/src/test/java/test/org/apache/spark/sql/JavaDatasetSuite.java
+++ b/sql/core/src/test/java/test/org/apache/spark/sql/JavaDatasetSuite.java
@@ -246,29 +246,6 @@ public class JavaDatasetSuite implements Serializable {
   }
 
   @Test
-  public void testGroupByColumn() {
-    List<String> data = Arrays.asList("a", "foo", "bar");
-    Dataset<String> ds = context.createDataset(data, Encoders.STRING());
-    KeyValueGroupedDataset<Integer, String> grouped =
-      ds.groupByKey(length(col("value"))).keyAs(Encoders.INT());
-
-    Dataset<String> mapped = grouped.mapGroups(
-      new MapGroupsFunction<Integer, String, String>() {
-        @Override
-        public String call(Integer key, Iterator<String> data) throws Exception {
-          StringBuilder sb = new StringBuilder(key.toString());
-          while (data.hasNext()) {
-            sb.append(data.next());
-          }
-          return sb.toString();
-        }
-      },
-      Encoders.STRING());
-
-    Assert.assertEquals(asSet("1a", "3foobar"), toSet(mapped.collectAsList()));
-  }
-
-  @Test
   public void testSelect() {
     List<Integer> data = Arrays.asList(2, 6);
     Dataset<Integer> ds = context.createDataset(data, Encoders.INT());
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/DatasetCacheSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/DatasetCacheSuite.scala
index 2e5179a8d2..942cc09b6d 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/DatasetCacheSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/DatasetCacheSuite.scala
@@ -63,7 +63,7 @@ class DatasetCacheSuite extends QueryTest with SharedSQLContext {
 
   test("persist and then groupBy columns asKey, map") {
     val ds = Seq(("a", 10), ("a", 20), ("b", 1), ("b", 2), ("c", 1)).toDS()
-    val grouped = ds.groupByKey($"_1").keyAs[String]
+    val grouped = ds.groupByKey(_._1)
     val agged = grouped.mapGroups { case (g, iter) => (g, iter.map(_._2).sum) }
     agged.persist()
 
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/DatasetSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/DatasetSuite.scala
index 0bcc512d71..553bc436a6 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/DatasetSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/DatasetSuite.scala
@@ -322,55 +322,6 @@ class DatasetSuite extends QueryTest with SharedSQLContext {
     )
   }
 
-  test("groupBy columns, map") {
-    val ds = Seq(("a", 10), ("a", 20), ("b", 1), ("b", 2), ("c", 1)).toDS()
-    val grouped = ds.groupByKey($"_1")
-    val agged = grouped.mapGroups { case (g, iter) => (g.getString(0), iter.map(_._2).sum) }
-
-    checkDataset(
-      agged,
-      ("a", 30), ("b", 3), ("c", 1))
-  }
-
-  test("groupBy columns, count") {
-    val ds = Seq("a" -> 1, "b" -> 1, "a" -> 2).toDS()
-    val count = ds.groupByKey($"_1").count()
-
-    checkDataset(
-      count,
-      (Row("a"), 2L), (Row("b"), 1L))
-  }
-
-  test("groupBy columns asKey, map") {
-    val ds = Seq(("a", 10), ("a", 20), ("b", 1), ("b", 2), ("c", 1)).toDS()
-    val grouped = ds.groupByKey($"_1").keyAs[String]
-    val agged = grouped.mapGroups { case (g, iter) => (g, iter.map(_._2).sum) }
-
-    checkDataset(
-      agged,
-      ("a", 30), ("b", 3), ("c", 1))
-  }
-
-  test("groupBy columns asKey tuple, map") {
-    val ds = Seq(("a", 10), ("a", 20), ("b", 1), ("b", 2), ("c", 1)).toDS()
-    val grouped = ds.groupByKey($"_1", lit(1)).keyAs[(String, Int)]
-    val agged = grouped.mapGroups { case (g, iter) => (g, iter.map(_._2).sum) }
-
-    checkDataset(
-      agged,
-      (("a", 1), 30), (("b", 1), 3), (("c", 1), 1))
-  }
-
-  test("groupBy columns asKey class, map") {
-    val ds = Seq(("a", 10), ("a", 20), ("b", 1), ("b", 2), ("c", 1)).toDS()
-    val grouped = ds.groupByKey($"_1".as("a"), lit(1).as("b")).keyAs[ClassData]
-    val agged = grouped.mapGroups { case (g, iter) => (g, iter.map(_._2).sum) }
-
-    checkDataset(
-      agged,
-      (ClassData("a", 1), 30), (ClassData("b", 1), 3), (ClassData("c", 1), 1))
-  }
-
   test("typed aggregation: expr") {
     val ds = Seq(("a", 10), ("a", 20), ("b", 1), ("b", 2), ("c", 1)).toDS()