[SPARK-19065][SQL]Don't inherit expression id in dropDuplicates

sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala

@@ -2003,10 +2003,7 @@ class Dataset[T] private[sql](
       if (groupColExprIds.contains(attr.exprId)) {
         attr
       } else {
-        // Removing duplicate rows should not change output attributes. We should keep
-        // the original exprId of the attribute. Otherwise, to select a column in original
-        // dataset will cause analysis exception due to unresolved attribute.
-        Alias(new First(attr).toAggregateExpression(), attr.name)(exprId = attr.exprId)
+        Alias(new First(attr).toAggregateExpression(), attr.name)()
       }
     }
     Aggregate(groupCols, aggCols, logicalPlan)

sql/core/src/test/scala/org/apache/spark/sql/DatasetSuite.scala

@@ -898,13 +898,6 @@ class DatasetSuite extends QueryTest with SharedSQLContext {
       (1, 2), (1, 1), (2, 1), (2, 2))
   }
 
-  test("dropDuplicates should not change child plan output") {
-    val ds = Seq(("a", 1), ("a", 2), ("b", 1), ("a", 1)).toDS()
-    checkDataset(
-      ds.dropDuplicates("_1").select(ds("_1").as[String], ds("_2").as[Int]),
-      ("a", 1), ("b", 1))
-  }
-
   test("SPARK-16097: Encoders.tuple should handle null object correctly") {
     val enc = Encoders.tuple(Encoders.tuple(Encoders.STRING, Encoders.STRING), Encoders.STRING)
     val data = Seq((("a", "b"), "c"), (null, "d"))

sql/core/src/test/scala/org/apache/spark/sql/streaming/StreamSuite.scala

@@ -304,6 +304,32 @@ class StreamSuite extends StreamTest {
       q.stop()
     }
   }
+
+  test("SPARK-19065: dropDuplicates should not create expressions using the same id") {
+    withTempPath { testPath =>
+      val data = Seq((1, 2), (2, 3), (3, 4))
+      data.toDS.write.mode("overwrite").json(testPath.getCanonicalPath)
+      val schema = spark.read.json(testPath.getCanonicalPath).schema
+      val query = spark
+        .readStream
+        .schema(schema)
+        .json(testPath.getCanonicalPath)
+        .dropDuplicates("_1")
+        .writeStream
+        .format("memory")
+        .queryName("testquery")
+        .outputMode("complete")
+        .start()
+      try {
+        query.processAllAvailable()
+        if (query.exception.isDefined) {
+          throw query.exception.get
+        }
+      } finally {
+        query.stop()
+      }
+    }
+  }
 }
 
 /**