Support Min/Max for Timestamp

api/src/main/java/io/druid/data/input/impl/TimestampSpec.java

@@ -88,15 +88,19 @@ public DateTime getMissingValue()
 
   public DateTime extractTimestamp(Map<String, Object> input)
   {
-    final Object o = input.get(timestampColumn);
+    return parseDateTime(input.get(timestampColumn));
+  }
+
+  public DateTime parseDateTime(Object input)
+  {
     DateTime extracted = missingValue;
-    if (o != null) {
-      if (o.equals(parseCtx.lastTimeObject)) {
+    if (input != null) {
+      if (input.equals(parseCtx.lastTimeObject)) {
         extracted = parseCtx.lastDateTime;
       } else {
         ParseCtx newCtx = new ParseCtx();
-        newCtx.lastTimeObject = o;
-        extracted = timestampConverter.apply(o);
+        newCtx.lastTimeObject = input;
+        extracted = timestampConverter.apply(input);
         newCtx.lastDateTime = extracted;
         parseCtx = newCtx;
       }

docs/content/development/extensions-contrib/time-min-max.md

@@ -0,0 +1,85 @@
+---
+layout: doc_page
+---
+
+# Timestamp Min/Max aggregators
+
+To use this extension, make sure to [include](../../operations/including-extensions.html) `druid-time-min-max`.
+
+These aggregators enable more precise calculation of min and max time of given events than `__time` column whose granularity is sparse, the same as query granularity.
+To use this feature, a "timeMin" or "timeMax" aggregator must be included at indexing time. 
+They can apply to any columns that can be converted to timestamp, which include Long, DateTime, Timestamp, and String types.
+
+For example, when a data set consists of timestamp, dimension, and metric value like followings.
+
+```
+2015-07-28T01:00:00.000Z  A  1
+2015-07-28T02:00:00.000Z  A  1
+2015-07-28T03:00:00.000Z  A  1
+2015-07-28T04:00:00.000Z  B  1
+2015-07-28T05:00:00.000Z  A  1
+2015-07-28T06:00:00.000Z  B  1
+2015-07-29T01:00:00.000Z  C  1
+2015-07-29T02:00:00.000Z  C  1
+2015-07-29T03:00:00.000Z  A  1
+2015-07-29T04:00:00.000Z  A  1
+```
+
+At ingestion time, timeMin and timeMax aggregator can be included as other aggregators.
+
+```json
+{
+    "type": "timeMin",
+    "name": "tmin",
+    "fieldName": "<field_name, typically column specified in timestamp spec>"
+}
+```
+
+```json
+{
+    "type": "timeMax",
+    "name": "tmax",
+    "fieldName": "<field_name, typically column specified in timestamp spec>"
+}
+```
+
+`name` is output name of aggregator and can be any string. `fieldName` is typically column specified in timestamp spec but can be any column that can be converted to timestamp.
+
+To query for results, the same aggregators "timeMin" and "timeMax" is used. 
+
+```json
+{
+  "queryType": "groupBy",
+  "dataSource": "timeMinMax",
+  "granularity": "DAY",
+  "dimensions": ["product"],
+  "aggregations": [
+    {
+      "type": "count",
+      "name": "count"
+    }
+    {
+      "type": "timeMin",
+      "name": "<output_name of timeMin>",
+      "fieldName": "tmin"
+    },
+    {
+      "type": "timeMax",
+      "name": "<output_name of timeMax>",
+      "fieldName": "tmax"
+    }
+  ],
+  "intervals": [
+    "2010-01-01T00:00:00.000Z/2020-01-01T00:00:00.000Z"
+  ]
+}
+```
+
+Then, result has min and max of timestamp, which is finer than query granularity.
+
+```
+2015-07-28T00:00:00.000Z A 4 2015-07-28T01:00:00.000Z 2015-07-28T05:00:00.000Z
+2015-07-28T00:00:00.000Z B 2 2015-07-28T04:00:00.000Z 2015-07-28T06:00:00.000Z
+2015-07-29T00:00:00.000Z A 2 2015-07-29T03:00:00.000Z 2015-07-29T04:00:00.000Z
+2015-07-29T00:00:00.000Z C 2 2015-07-29T01:00:00.000Z 2015-07-29T02:00:00.000Z
+```

docs/content/development/extensions.md

@@ -58,6 +58,7 @@ All of these community extensions can be downloaded using *pull-deps* with the c
 |druid-parquet-extensions|Support for data in Apache Parquet data format. Requires druid-avro-extensions to be loaded.|[link](../development/extensions-contrib/parquet.html)|
 |druid-rabbitmq|RabbitMQ firehose.|[link](../development/extensions-contrib/rabbitmq.html)|
 |druid-rocketmq|RocketMQ firehose.|[link](../development/extensions-contrib/rocketmq.html)|
+|druid-time-min-max|Min/Max aggregator for timestamp.|[link](../development/extensions-contrib/time-min-max.html)|
 |sqlserver-metadata-storage|Microsoft SqlServer deep storage.|[link](../development/extensions-contrib/sqlserver.html)|
 |graphite-emitter|Graphite metrics emitter|[link](../development/extensions-contrib/graphite.html)|
 |statsd-emitter|StatsD metrics emitter|[link](../development/extensions-contrib/statsd.html)|

extensions-contrib/time-min-max/pom.xml

@@ -0,0 +1,79 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+ ~ 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.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <parent>
+    <artifactId>druid</artifactId>
+    <groupId>io.druid</groupId>
+    <version>0.9.3-SNAPSHOT</version>
+    <relativePath>../../pom.xml</relativePath>
+  </parent>
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>io.druid.extensions.contrib</groupId>
+  <artifactId>druid-time-min-max</artifactId>
+  <name>druid-time-min-max</name>
+  <description>Min/Max of timestamp</description>
+
+  <dependencies>
+    <dependency>
+      <groupId>io.druid</groupId>
+      <artifactId>druid-api</artifactId>
+      <version>${project.parent.version}</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.druid</groupId>
+      <artifactId>druid-processing</artifactId>
+      <version>${project.parent.version}</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.druid</groupId>
+      <artifactId>druid-common</artifactId>
+      <version>${project.parent.version}</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.easymock</groupId>
+      <artifactId>easymock</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.druid</groupId>
+      <artifactId>druid-processing</artifactId>
+      <version>${project.parent.version}</version>
+      <type>test-jar</type>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.druid</groupId>
+      <artifactId>druid-server</artifactId>
+      <version>${project.parent.version}</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+</project>

extensions-contrib/time-min-max/src/main/java/io/druid/query/aggregation/TimestampAggregator.java

@@ -0,0 +1,111 @@
+/*
+ * 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.query.aggregation;
+
+import io.druid.data.input.impl.TimestampSpec;
+import io.druid.segment.ObjectColumnSelector;
+
+import java.util.Comparator;
+
+public class TimestampAggregator implements Aggregator
+{
+  static final Comparator COMPARATOR = LongMaxAggregator.COMPARATOR;
+
+  static long combineValues(Object lhs, Object rhs)
+  {
+    return Math.max(((Number)lhs).longValue(), ((Number)rhs).longValue());
+  }
+
+  private final ObjectColumnSelector selector;
+  private final String name;
+  private final TimestampSpec timestampSpec;
+  private final Comparator<Long> comparator;
+  private final Long initValue;
+
+  private long most;
+
+  public TimestampAggregator(
+      String name,
+      ObjectColumnSelector selector,
+      TimestampSpec timestampSpec,
+      Comparator<Long> comparator,
+      Long initValue
+  )
+  {
+    this.name = name;
+    this.selector = selector;
+    this.timestampSpec = timestampSpec;
+    this.comparator = comparator;
+    this.initValue = initValue;
+
+    reset();
+  }
+
+  @Override
+  public void aggregate() {
+    Long value = TimestampAggregatorFactory.convertLong(timestampSpec, selector.get());
+
+    if (value != null) {
+      most = comparator.compare(most, value) > 0 ? most : value;
+    }
+  }
+
+  @Override
+  public void reset()
+  {
+    most = initValue;
+  }
+
+  @Override
+  public Object get()
+  {
+    return most;
+  }
+
+  @Override
+  public float getFloat()
+  {
+    return (float) most;
+  }
+
+  @Override
+  public String getName()
+  {
+    return name;
+  }
+
+  @Override
+  public void close()
+  {
+    // no resource to cleanup
+  }
+
+  @Override
+  public long getLong()
+  {
+    return most;
+  }
+
+  @Override
+  public Aggregator clone()
+  {
+    return new TimestampAggregator(name, selector, timestampSpec, comparator, initValue);
+  }
+}