diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/ObjectType.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/ObjectType.scala
index b7b1acc58242ef19d7154bedc18ea45099a682da..c741a2dd3ea3041151b431f52f684ee05bff4641 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/ObjectType.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/ObjectType.scala
@@ -37,8 +37,7 @@ private[sql] object ObjectType extends AbstractDataType {
  * outside of the execution engine.
  */
 private[sql] case class ObjectType(cls: Class[_]) extends DataType {
-  override def defaultSize: Int =
-    throw new UnsupportedOperationException("No size estimation available for objects.")
+  override def defaultSize: Int = 4096
 
   def asNullable: DataType = this
 
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 a6e3bd3a91a15555be42f127ef4bb23fe432f3bf..eee21acf7510b6770f846b9755bbd093fed2af5f 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
@@ -630,6 +630,29 @@ class DatasetSuite extends QueryTest with SharedSQLContext {
     // Make sure the generated code for this plan can compile and execute.
     checkDataset(wideDF.map(_.getLong(0)), 0L until 10 : _*)
   }
+
+  test("SPARK-14838: estimating sizeInBytes in operators with ObjectProducer shouldn't fail") {
+    val dataset = Seq(
+      (0, 3, 54f),
+      (0, 4, 44f),
+      (0, 5, 42f),
+      (1, 3, 39f),
+      (1, 5, 33f),
+      (1, 4, 26f),
+      (2, 3, 51f),
+      (2, 5, 45f),
+      (2, 4, 30f)
+    ).toDF("user", "item", "rating")
+
+    val actual = dataset
+      .select("user", "item")
+      .as[(Int, Int)]
+      .groupByKey(_._1)
+      .mapGroups { case (src, ids) => (src, ids.map(_._2).toArray) }
+      .toDF("id", "actual")
+
+    dataset.join(actual, dataset("user") === actual("id")).collect()
+  }
 }
 
 case class OtherTuple(_1: String, _2: Int)