[GitHub] [incubator-druid] jihoonson commented on a change in pull request #7331: TDigest backed sketch aggregators

[GitBox <gi...@apache.org>]

jihoonson commented on a change in pull request #7331: TDigest backed sketch aggregators
URL: https://github.com/apache/incubator-druid/pull/7331#discussion_r278355948
 
 

 ##########
 File path: extensions-contrib/tdigestsketch/src/main/java/org/apache/druid/query/aggregation/tdigestsketch/TDigestBuildSketchAggregator.java
 ##########
 @@ -0,0 +1,92 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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 org.apache.druid.query.aggregation.tdigestsketch;
+
+import com.tdunning.math.stats.MergingDigest;
+import org.apache.druid.java.util.common.IAE;
+import org.apache.druid.query.aggregation.Aggregator;
+import org.apache.druid.segment.ColumnValueSelector;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+
+/**
+ * Aggregator to build tDigest sketches on numeric values.
+ */
+public class TDigestBuildSketchAggregator implements Aggregator
+{
+
+  private final ColumnValueSelector selector;
+
+  // Default compression
+  static final int DEFAULT_COMPRESSION = 50;
+
+  @GuardedBy("this")
+  private MergingDigest histogram;
+
+
+  public TDigestBuildSketchAggregator(ColumnValueSelector selector, Integer compression)
+  {
+    this.selector = selector;
+    if (compression != null) {
+      this.histogram = new MergingDigest(compression);
+    } else {
+      this.histogram = new MergingDigest(DEFAULT_COMPRESSION);
+    }
+  }
+
+  @Override
+  public synchronized void aggregate()
+  {
+    if (selector.getObject() instanceof Number) {
+      histogram.add(((Number) selector.getObject()).doubleValue());
+    } else {
+      throw new IAE("Expected a number, received "
+                    + selector.getObject()
+                    + " of type "
+                    + selector.getObject());
+    }
+  }
+
+  @Nullable
+  @Override
+  public synchronized Object get()
+  {
+    return histogram;
+  }
+
+  @Override
+  public float getFloat()
+  {
+    throw new UnsupportedOperationException("not implemented");
 
 Review comment:
   Maybe it should say "Casting to float type is not supported". Similar for `getLong()`.

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services

---------------------------------------------------------------------
To unsubscribe, e-mail: commits-unsubscribe@druid.apache.org
For additional commands, e-mail: commits-help@druid.apache.org