fix groupBy ordering casing bug

histogram/src/test/java/io/druid/query/aggregation/histogram/ApproximateHistogramGroupByQueryTest.java

@@ -158,7 +158,7 @@ public class ApproximateHistogramGroupByQueryTest
             Arrays.<DimensionSpec>asList(
                 new DefaultDimensionSpec(
                     QueryRunnerTestHelper.providerDimension,
-                    "provider"
+                    "proViderAlias"
                 )
             )
         )
@@ -167,7 +167,7 @@ public class ApproximateHistogramGroupByQueryTest
             new DefaultLimitSpec(
                 Lists.newArrayList(
                     new OrderByColumnSpec(
-                        "provider",
+                        "proViderAlias",
                         OrderByColumnSpec.Direction.DESCENDING
                     )
                 ), 1
@@ -189,7 +189,7 @@ public class ApproximateHistogramGroupByQueryTest
     List<Row> expectedResults = Arrays.asList(
         GroupByQueryRunnerTestHelper.createExpectedRow(
             "1970-01-01T00:00:00.000Z",
-            "provider", "upfront",
+            "provideralias", "upfront",
             "rows", 186L,
             "quantile", 880.9881f,
             "apphisto",

processing/src/main/java/io/druid/query/groupby/orderby/DefaultLimitSpec.java

@@ -173,7 +173,7 @@ public class DefaultLimitSpec implements LimitSpec
                          public String apply(Row input)
                          {
                            // Multi-value dimensions have all been flattened at this point;
-                           final List<String> dimList = input.getDimension(dimension);
+                           final List<String> dimList = input.getDimension(dimension.toLowerCase());
                            return dimList.isEmpty() ? null : dimList.get(0);
                          }
                        }

processing/src/test/java/io/druid/query/groupby/GroupByQueryRunnerTest.java

@@ -733,6 +733,48 @@ public class GroupByQueryRunnerTest
     );
   }
 
+  @Test
+  public void testGroupByWithMixedCasingOrdering()
+  {
+    GroupByQuery query = new GroupByQuery.Builder()
+        .setDataSource(QueryRunnerTestHelper.dataSource)
+        .setGranularity(QueryRunnerTestHelper.allGran)
+        .setDimensions(
+            Arrays.<DimensionSpec>asList(
+                new DefaultDimensionSpec(
+                    QueryRunnerTestHelper.providerDimension,
+                    "ProviderAlias"
+                )
+            )
+        )
+        .setInterval(QueryRunnerTestHelper.fullOnInterval)
+        .setLimitSpec(
+            new DefaultLimitSpec(
+                Lists.newArrayList(
+                    new OrderByColumnSpec(
+                        "providerALIAS",
+                        OrderByColumnSpec.Direction.DESCENDING
+                    )
+                ), 3
+            )
+        )
+        .setAggregatorSpecs(
+            Lists.<AggregatorFactory>newArrayList(
+                QueryRunnerTestHelper.rowsCount
+            )
+        )
+        .build();
+
+    List<Row> expectedResults = Arrays.asList(
+        GroupByQueryRunnerTestHelper.createExpectedRow("1970-01-01T00:00:00.000Z", "provideralias", "upfront", "rows", 186L),
+        GroupByQueryRunnerTestHelper.createExpectedRow("1970-01-01T00:00:00.000Z", "provideralias", "total_market", "rows", 186L),
+        GroupByQueryRunnerTestHelper.createExpectedRow("1970-01-01T00:00:00.000Z", "provideralias", "spot", "rows", 837L)
+    );
+
+    Iterable<Row> results = GroupByQueryRunnerTestHelper.runQuery(factory, runner, query);
+    TestHelper.assertExpectedObjects(expectedResults, results, "order-limit");
+  }
+
   @Test
   public void testHavingSpec()
   {