First and Last Aggregator

common/src/main/java/io/druid/collections/SerializablePair.java

@@ -0,0 +1,45 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.druid.collections;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import io.druid.java.util.common.Pair;
+
+public class SerializablePair<T1, T2> extends Pair<T1, T2>
+{
+  @JsonCreator
+  public SerializablePair(@JsonProperty("lhs") T1 lhs, @JsonProperty("rhs") T2 rhs)
+  {
+    super(lhs, rhs);
+  }
+
+  @JsonProperty
+  public T1 getLhs()
+  {
+    return lhs;
+  }
+
+  @JsonProperty
+  public T2 getRhs()
+  {
+    return rhs;
+  }
+}

common/src/test/java/io/druid/collections/SerializablePairTest.java

@@ -0,0 +1,51 @@
+/*
+ * Licensed to Metamarkets Group Inc. (Metamarkets) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Metamarkets licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package io.druid.collections;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.IOException;
+
+public class SerializablePairTest
+{
+  private static final ObjectMapper jsonMapper = new ObjectMapper();
+
+  @Test
+  public void testBytesSerde() throws IOException
+  {
+    SerializablePair pair = new SerializablePair<>(5L, 9L);
+    byte[] bytes = jsonMapper.writeValueAsBytes(pair);
+    SerializablePair<Number, Number> deserializedPair = jsonMapper.readValue(bytes, SerializablePair.class);
+    Assert.assertEquals(pair.lhs, deserializedPair.lhs.longValue());
+    Assert.assertEquals(pair.rhs, deserializedPair.rhs.longValue());
+  }
+
+  @Test
+  public void testStringSerde() throws IOException
+  {
+    SerializablePair pair = new SerializablePair<>(5L, 9L);
+    String str = jsonMapper.writeValueAsString(pair);
+    SerializablePair<Number, Number> deserializedPair = jsonMapper.readValue(str, SerializablePair.class);
+    Assert.assertEquals(pair.lhs, deserializedPair.lhs.longValue());
+    Assert.assertEquals(pair.rhs, deserializedPair.rhs.longValue());
+  }
+}

docs/content/querying/aggregations.md

@@ -76,6 +76,60 @@ Computes the sum of values as 64-bit floating point value. Similar to `longSum`
 { "type" : "longMax", "name" : <output_name>, "fieldName" : <metric_name> }
 ```
 
+### First / Last aggregator
+
+First and Last aggregator cannot be used in ingestion spec, and should only be specified as part of queries.
+
+Note that queries with first/last aggregators on a segment created with rollup enabled will return the rolled up value, and not the last value within the raw ingested data.
+
+#### `doubleFirst` aggregator
+
+`doubleFirst` computes the metric value with the minimum timestamp or 0 if no row exist
+
+```json
+{
+  "type" : "doubleFirst",
+  "name" : <output_name>,
+  "fieldName" : <metric_name>
+}
+```
+
+#### `doubleLast` aggregator
+
+`doubleLast` computes the metric value with the maximum timestamp or 0 if no row exist
+
+```json
+{
+  "type" : "doubleLast",
+  "name" : <output_name>,
+  "fieldName" : <metric_name>
+}
+```
+
+#### `longFirst` aggregator
+
+`longFirst` computes the metric value with the minimum timestamp or 0 if no row exist
+
+```json
+{
+  "type" : "longFirst",
+  "name" : <output_name>,
+  "fieldName" : <metric_name>
+}
+```
+
+#### `longLast` aggregator
+
+`longLast` computes the metric value with the maximum timestamp or 0 if no row exist
+
+```json
+{ 
+  "type" : "longLast",
+  "name" : <output_name>, 
+  "fieldName" : <metric_name>,
+}
+```
+
 ### JavaScript aggregator
 
 Computes an arbitrary JavaScript function over a set of columns (both metrics and dimensions are allowed). Your