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Posted to commits@pinot.apache.org by "mayankshriv (via GitHub)" <gi...@apache.org> on 2023/02/16 19:48:07 UTC
[GitHub] [pinot] mayankshriv commented on a diff in pull request #10288: Add Theta Sketch Aggregation for StarTree Indexes
mayankshriv commented on code in PR #10288:
URL: https://github.com/apache/pinot/pull/10288#discussion_r1108948702
##########
pinot-spi/src/main/java/org/apache/pinot/spi/utils/CommonConstants.java:
##########
@@ -91,6 +91,10 @@ public static class Helix {
public static final String DEFAULT_HYPERLOGLOG_LOG2M_KEY = "default.hyperloglog.log2m";
public static final int DEFAULT_HYPERLOGLOG_LOG2M = 8;
+ // 2 to the power of 16, for tradeoffs see datasketches library documentation:
+ // https://datasketches.apache.org/docs/Theta/ThetaErrorTable.html
+ public static final int DEFAULT_THETA_SKETCH_NOMINAL_ENTRIES = 65536;
Review Comment:
We might want to make this configurable to allow for accuracy vs storage tradeoff.
##########
pinot-segment-local/src/main/java/org/apache/pinot/segment/local/aggregator/DistinctCountThetaSketchValueAggregator.java:
##########
@@ -0,0 +1,117 @@
+/**
+ * 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.pinot.segment.local.aggregator;
+
+import org.apache.datasketches.theta.SingleItemSketch;
+import org.apache.datasketches.theta.Sketch;
+import org.apache.datasketches.theta.Union;
+import org.apache.pinot.segment.local.utils.CustomSerDeUtils;
+import org.apache.pinot.segment.spi.AggregationFunctionType;
+import org.apache.pinot.spi.data.FieldSpec.DataType;
+import org.apache.pinot.spi.utils.CommonConstants;
+
+
+public class DistinctCountThetaSketchValueAggregator implements ValueAggregator<Object, Sketch> {
+ public static final DataType AGGREGATED_VALUE_TYPE = DataType.BYTES;
+
+ @Override
+ public AggregationFunctionType getAggregationType() {
+ return AggregationFunctionType.DISTINCTCOUNTTHETASKETCH;
+ }
+
+ @Override
+ public DataType getAggregatedValueType() {
+ return AGGREGATED_VALUE_TYPE;
+ }
+
+ // This changes a lot similar to the Bitmap aggregator
+ private int _maxByteSize;
+
+ // Utility method to create a theta sketch with one item in it
+ private Sketch singleItemSketch(Object rawValue) {
+ return SingleItemSketch.create(rawValue.hashCode()).compact();
+ }
+
+ // Utility method to merge two sketches
+ private Sketch union(Sketch left, Sketch right) {
+ // TODO: Handle configurable nominal entries for StarTreeBuilder
+ Union u = Union.builder()
+ .setNominalEntries(CommonConstants.Helix.DEFAULT_THETA_SKETCH_NOMINAL_ENTRIES)
+ .buildUnion();
+ u.update(left);
+ u.update(right);
+ return u.getResult().compact();
+ }
+
+ @Override
+ public Sketch getInitialAggregatedValue(Object rawValue) {
+ Sketch initialValue;
+ if (rawValue instanceof byte[]) {
+ byte[] bytes = (byte[]) rawValue;
+ initialValue = deserializeAggregatedValue(bytes);
+ _maxByteSize = Math.max(_maxByteSize, bytes.length);
+ } else {
+ initialValue = singleItemSketch(rawValue);
+ _maxByteSize = Math.max(_maxByteSize, initialValue.getCurrentBytes(true));
+ }
+ return initialValue;
Review Comment:
Yeah, this is more of a contract than enforcement.
##########
pinot-segment-local/src/main/java/org/apache/pinot/segment/local/aggregator/DistinctCountThetaSketchValueAggregator.java:
##########
@@ -0,0 +1,138 @@
+/**
+ * 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.pinot.segment.local.aggregator;
+
+import org.apache.datasketches.theta.Sketch;
+import org.apache.datasketches.theta.Sketches;
+import org.apache.datasketches.theta.Union;
+import org.apache.datasketches.theta.UpdateSketch;
+import org.apache.pinot.segment.local.utils.CustomSerDeUtils;
+import org.apache.pinot.segment.spi.AggregationFunctionType;
+import org.apache.pinot.spi.data.FieldSpec.DataType;
+import org.apache.pinot.spi.utils.CommonConstants;
+
+
+public class DistinctCountThetaSketchValueAggregator implements ValueAggregator<Object, Sketch> {
+ public static final DataType AGGREGATED_VALUE_TYPE = DataType.BYTES;
+
+ Union _union;
+
+ public DistinctCountThetaSketchValueAggregator() {
+ // TODO: Handle configurable nominal entries for StarTreeBuilder
+ _union = Union.builder()
+ .setNominalEntries(CommonConstants.Helix.DEFAULT_THETA_SKETCH_NOMINAL_ENTRIES)
+ .buildUnion();
+ };
+
+ @Override
+ public AggregationFunctionType getAggregationType() {
+ return AggregationFunctionType.DISTINCTCOUNTTHETASKETCH;
+ }
+
+ @Override
+ public DataType getAggregatedValueType() {
+ return AGGREGATED_VALUE_TYPE;
+ }
+
+ // This changes a lot similar to the Bitmap aggregator
+ private int _maxByteSize;
+
+ // Utility method to create a theta sketch with one item in it
+ private Sketch singleItemSketch(Object rawValue) {
+ // TODO: Handle configurable nominal entries for StarTreeBuilder
+ UpdateSketch sketch = Sketches.updateSketchBuilder()
+ .setNominalEntries(CommonConstants.Helix.DEFAULT_THETA_SKETCH_NOMINAL_ENTRIES)
+ .build();
+ if (rawValue instanceof String) {
Review Comment:
There are other data types (eg `Boolean`, `JSON`) etc that might need to be handled. Seems like other valueAggregators have the same issue.
cc: @Jackie-Jiang
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