Merge pull request #516 from metamx/alphanumeric-topn

Alpha-numeric sorting for topN

docs/content/TopNMetricSpec.md

@@ -43,3 +43,20 @@ The grammar for dimension values sorted lexicographically is as follows:
 |--------|-----------|---------|
 |type|this indicates a lexicographic sort|yes|
 |previousStop|the starting point of the lexicographic sort. For example, if a previousStop value is 'b', all values before 'b' are discarded. This field can be used to paginate through all the dimension values.|no|
+
+## AlphaNumeric TopNMetricSpec
+
+Sort dimension values in alpha-numeric order, i.e treating numbers differently from other characters in sorting the values.
+See [http://www.davekoelle.com/alphanum.html](http://www.davekoelle.com/alphanum.html) for details on how the algorithm works.
+
+```json
+"metric": {
+    "type": "alphaNumeric",
+    "previousStop": "<previousStop_value>"
+}
+```
+
+|property|description|required?|
+|--------|-----------|---------|
+|type|this indicates an alpha-numeric sort|yes|
+|previousStop|the starting point of the alpha-numeric sort. For example, if a previousStop value is 'b', all values before 'b' are discarded. This field can be used to paginate through all the dimension values.|no|

pom.xml

@@ -406,6 +406,11 @@
                 <artifactId>httpcore</artifactId>
                 <version>4.2</version>
             </dependency>
+            <dependency>
+                <groupId>com.davekoelle</groupId>
+                <artifactId>alphanum</artifactId>
+                <version>1.0.3</version>
+            </dependency>
             <dependency>
                 <groupId>org.apache.hadoop</groupId>
                 <artifactId>hadoop-client</artifactId>

processing/pom.xml

@@ -78,6 +78,10 @@
             <artifactId>rhino</artifactId>
             <version>1.7R4</version>
         </dependency>
+        <dependency>
+            <groupId>com.davekoelle</groupId>
+            <artifactId>alphanum</artifactId>
+        </dependency>
 
 
         <!-- Tests -->

processing/src/main/java/io/druid/query/topn/AlphaNumericTopNMetricSpec.java

@@ -0,0 +1,78 @@
+/*
+ * Druid - a distributed column store.
+ * Copyright (C) 2012, 2013, 2014  Metamarkets Group Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+package io.druid.query.topn;
+
+import com.davekoelle.alphanum.AlphanumComparator;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.base.Charsets;
+import io.druid.query.aggregation.AggregatorFactory;
+import io.druid.query.aggregation.PostAggregator;
+
+import java.nio.ByteBuffer;
+import java.util.Comparator;
+import java.util.List;
+
+public class AlphaNumericTopNMetricSpec extends LexicographicTopNMetricSpec
+{
+  private static final byte CACHE_TYPE_ID = 0x2;
+
+  private final String previousStop;
+
+  @JsonCreator
+  public AlphaNumericTopNMetricSpec(
+      @JsonProperty("previousStop") String previousStop
+  )
+  {
+    super(previousStop);
+    this.previousStop = (previousStop == null) ? "" : previousStop;
+  }
+
+  @Override
+  public Comparator getComparator(List<AggregatorFactory> aggregatorSpecs, List<PostAggregator> postAggregatorSpecs)
+  {
+    return new AlphanumComparator();
+  }
+
+  @Override
+  public byte[] getCacheKey()
+  {
+    byte[] previousStopBytes = previousStop.getBytes(Charsets.UTF_8);
+
+    return ByteBuffer.allocate(1 + previousStopBytes.length)
+                     .put(CACHE_TYPE_ID)
+                     .put(previousStopBytes)
+                     .array();
+  }
+
+  @Override
+  public <T> TopNMetricSpecBuilder<T> configureOptimizer(TopNMetricSpecBuilder<T> builder)
+  {
+    return builder;
+  }
+
+  @Override
+  public String toString()
+  {
+    return "AlphaNumericTopNMetricSpec{" +
+           "previousStop='" + previousStop + '\'' +
+           '}';
+  }
+}

processing/src/main/java/io/druid/query/topn/TopNMetricSpec.java

@@ -35,6 +35,7 @@ import java.util.List;
 @JsonSubTypes(value = {
     @JsonSubTypes.Type(name = "numeric", value = NumericTopNMetricSpec.class),
     @JsonSubTypes.Type(name = "lexicographic", value = LexicographicTopNMetricSpec.class),
+    @JsonSubTypes.Type(name = "alphaNumeric", value = AlphaNumericTopNMetricSpec.class),
     @JsonSubTypes.Type(name = "inverted", value = InvertedTopNMetricSpec.class)
 })
 public interface TopNMetricSpec