timezone support in groupby query

client/src/main/java/com/metamx/druid/query/group/GroupByQueryQueryToolChest.java

@@ -32,6 +32,7 @@ import com.metamx.druid.Query;
 import com.metamx.druid.aggregation.AggregatorFactory;
 import com.metamx.druid.index.v1.IncrementalIndex;
 import com.metamx.druid.initialization.Initialization;
+import com.metamx.druid.input.MapBasedRow;
 import com.metamx.druid.input.Row;
 import com.metamx.druid.input.Rows;
 import com.metamx.druid.query.CacheStrategy;
@@ -119,7 +120,19 @@ public class GroupByQueryQueryToolChest implements QueryToolChest<Row, GroupByQu
             }
         );
 
-        return Sequences.simple(index.iterableWithPostAggregations(query.getPostAggregatorSpecs()));
+        // convert millis back to timestamp according to granularity to preserve time zone information
+        return Sequences.map(
+            Sequences.simple(index.iterableWithPostAggregations(query.getPostAggregatorSpecs())),
+            new Function<Row, Row>()
+            {
+              @Override
+              public Row apply(@Nullable Row input)
+              {
+                final MapBasedRow row = (MapBasedRow) input;
+                return new MapBasedRow(query.getGranularity().toDateTime(row.getTimestampFromEpoch()), row.getEvent());
+              }
+            }
+        );
       }
     };
   }

common/src/main/java/com/metamx/druid/input/MapBasedRow.java

@@ -37,7 +37,7 @@ import java.util.Map;
  */
 public class MapBasedRow implements Row
 {
-  private final long timestamp;
+  private final DateTime timestamp;
   private final Map<String, Object> event;
 
   @JsonCreator
@@ -46,22 +46,21 @@ public class MapBasedRow implements Row
       @JsonProperty("event")  Map<String, Object> event
   )
   {
-    this(timestamp.getMillis(), event);
+    this.timestamp = timestamp;
+    this.event = event;
   }
 
   public MapBasedRow(
       long timestamp,
       Map<String, Object> event
-  )
-  {
-    this.timestamp = timestamp;
-    this.event = event;
+  ) {
+    this(new DateTime(timestamp), event);
   }
 
   @Override
   public long getTimestampFromEpoch()
   {
-    return timestamp;
+    return timestamp.getMillis();
   }
 
   @Override
@@ -120,7 +119,7 @@ public class MapBasedRow implements Row
   @JsonProperty
   public DateTime getTimestamp()
   {
-    return new DateTime(timestamp);
+    return timestamp;
   }
 
   @JsonProperty
@@ -133,9 +132,38 @@ public class MapBasedRow implements Row
   public String toString()
   {
     return "MapBasedRow{" +
-           "timestamp=" + new DateTime(timestamp) +
+           "timestamp=" + timestamp +
            ", event=" + event +
            '}';
   }
 
+  @Override
+  public boolean equals(Object o)
+  {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+
+    MapBasedRow that = (MapBasedRow) o;
+
+    if (!event.equals(that.event)) {
+      return false;
+    }
+    if (!timestamp.equals(that.timestamp)) {
+      return false;
+    }
+
+    return true;
+  }
+
+  @Override
+  public int hashCode()
+  {
+    int result = timestamp.hashCode();
+    result = 31 * result + event.hashCode();
+    return result;
+  }
 }

server/src/main/java/com/metamx/druid/query/group/GroupByQueryEngine.java

@@ -43,6 +43,7 @@ import com.metamx.druid.index.v1.processing.DimensionSelector;
 import com.metamx.druid.input.MapBasedRow;
 import com.metamx.druid.input.Row;
 import com.metamx.druid.query.dimension.DimensionSpec;
+import org.joda.time.DateTime;
 import org.joda.time.Interval;
 
 import javax.annotation.Nullable;
@@ -347,7 +348,7 @@ public class GroupByQueryEngine
           .transform(
               new Function<Map.Entry<ByteBuffer, Integer>, Row>()
               {
-                private final long timestamp = cursor.getTime().getMillis();
+                private final DateTime timestamp = cursor.getTime();
                 private final int[] increments = positionMaintainer.getIncrements();
 
                 @Override

server/src/test/java/com/metamx/druid/query/group/GroupByTimeseriesQueryRunnerTest.java

@@ -112,7 +112,7 @@ public class GroupByTimeseriesQueryRunnerTest extends TimeseriesQueryRunnerTest
                     MapBasedRow row = (MapBasedRow) input;
 
                     return new Result<TimeseriesResultValue>(
-                        new DateTime(input.getTimestampFromEpoch()), new TimeseriesResultValue(row.getEvent())
+                        row.getTimestamp(), new TimeseriesResultValue(row.getEvent())
                     );
                   }
                 }