2 files changed, 12 insertions, 0 deletions
diff --git a/mllib/src/main/scala/org/apache/spark/ml/feature/StringIndexer.scala b/mllib/src/main/scala/org/apache/spark/ml/feature/StringIndexer.scala
index 912bd95a2e..555f1130e4 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/feature/StringIndexer.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/feature/StringIndexer.scala
@@ -150,6 +150,7 @@ class StringIndexerModel (
         "Skip StringIndexerModel.")
       return dataset
     }
+    validateAndTransformSchema(dataset.schema)
 
     val indexer = udf { label: String =>
       if (labelToIndex.contains(label)) {
diff --git a/mllib/src/test/scala/org/apache/spark/ml/feature/StringIndexerSuite.scala b/mllib/src/test/scala/org/apache/spark/ml/feature/StringIndexerSuite.scala
index 5d199ca9b5..0dbaed2522 100644
--- a/mllib/src/test/scala/org/apache/spark/ml/feature/StringIndexerSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/ml/feature/StringIndexerSuite.scala
@@ -118,6 +118,17 @@ class StringIndexerSuite
     assert(indexerModel.transform(df).eq(df))
   }
 
+  test("StringIndexerModel can't overwrite output column") {
+    val df = sqlContext.createDataFrame(Seq((1, 2), (3, 4))).toDF("input", "output")
+    val indexer = new StringIndexer()
+      .setInputCol("input")
+      .setOutputCol("output")
+      .fit(df)
+    intercept[IllegalArgumentException] {
+      indexer.transform(df)
+    }
+  }
+
   test("StringIndexer read/write") {
     val t = new StringIndexer()
       .setInputCol("myInputCol")