hfukada commented on code in PR #15049: URL: https://github.com/apache/druid/pull/15049#discussion_r1414577722
########## extensions-contrib/ddsketch/src/main/java/org/apache/druid/query/aggregation/ddsketch/DDSketchAggregatorFactory.java: ########## @@ -0,0 +1,339 @@ +/* + * 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.ddsketch; + +import com.datadoghq.sketch.ddsketch.DDSketch; +import com.datadoghq.sketch.ddsketch.DDSketches; +import com.fasterxml.jackson.annotation.JsonCreator; +import com.fasterxml.jackson.annotation.JsonProperty; +import com.fasterxml.jackson.annotation.JsonTypeName; +import org.apache.curator.shaded.com.google.common.math.IntMath; +import org.apache.druid.query.aggregation.AggregateCombiner; +import org.apache.druid.query.aggregation.Aggregator; +import org.apache.druid.query.aggregation.AggregatorFactory; +import org.apache.druid.query.aggregation.AggregatorFactoryNotMergeableException; +import org.apache.druid.query.aggregation.AggregatorUtil; +import org.apache.druid.query.aggregation.BufferAggregator; +import org.apache.druid.query.aggregation.ObjectAggregateCombiner; +import org.apache.druid.query.cache.CacheKeyBuilder; +import org.apache.druid.segment.ColumnSelectorFactory; +import org.apache.druid.segment.ColumnValueSelector; +import org.apache.druid.segment.column.ColumnType; + +import javax.annotation.Nonnull; +import javax.annotation.Nullable; +import java.util.Collections; +import java.util.Comparator; +import java.util.List; +import java.util.Objects; + +/** + * Aggregation operations over the ddsketch quantile sketch + * available on <a href="https://github.com/DataDog/sketches-java";>github</a> and described + * in the paper + * <a href="https://blog.acolyer.org/2019/09/06/ddsketch/";> + * Computing relative error quantiles using ddsketch</a>. + * <p> + */ +@JsonTypeName(DDSketchAggregatorFactory.TYPE_NAME) +public class DDSketchAggregatorFactory extends AggregatorFactory +{ + // Default relative error + public static final double DEFAULT_RELATIVE_ERROR = 0.01; + + // Default num bins + public static final int DEFAULT_NUM_BINS = 1000; + + @Nonnull + private final String name; + @Nonnull + private final String fieldName; + + private final double relativeError; + + private final int numBins; + + private final byte cacheTypeId; + + public static final String TYPE_NAME = "ddSketch"; + public static final ColumnType TYPE = ColumnType.ofComplex(TYPE_NAME); + + @JsonCreator + public DDSketchAggregatorFactory( + @JsonProperty("name") final String name, + @JsonProperty("fieldName") final String fieldName, + @JsonProperty("relativeError") final Double relativeError, + @JsonProperty("numBins") final Integer numBins + ) + { + this(name, fieldName, relativeError, numBins, AggregatorUtil.DDSKETCH_CACHE_TYPE_ID); + } + + DDSketchAggregatorFactory( + final String name, + final String fieldName, + @Nullable final Double relativeError, + @Nullable final Integer numBins, + final byte cacheTypeId + ) + { + this.name = Objects.requireNonNull(name, "Must have a valid, non-null aggregator name"); + this.fieldName = Objects.requireNonNull(fieldName, "Parameter fieldName must be specified"); + this.relativeError = relativeError == null ? DEFAULT_RELATIVE_ERROR : relativeError; + this.numBins = numBins == null ? DEFAULT_NUM_BINS : numBins; + this.cacheTypeId = cacheTypeId; + } + + + @Override + public byte[] getCacheKey() + { + return new CacheKeyBuilder( + cacheTypeId + ).appendString(fieldName).appendDouble(relativeError).appendInt(numBins).build(); + } + + + @Override + public Aggregator factorize(ColumnSelectorFactory metricFactory) + { + return new DDSketchAggregator(metricFactory.makeColumnValueSelector(fieldName), relativeError, numBins); + } + + @Override + public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory) + { + return new DDSketchBufferAggregator(metricFactory.makeColumnValueSelector(fieldName), relativeError, numBins); + } + + public static final Comparator<DDSketch> COMPARATOR = Comparator.nullsFirst( + Comparator.comparingLong(a -> a.serializedSize()) + ); + + @Override + public Comparator getComparator() + { + return COMPARATOR; + } + + @Override + public Object combine(@Nullable Object lhs, @Nullable Object rhs) + { + if (lhs == null) { + return rhs; + } + if (rhs == null) { + return lhs; + } + DDSketch union = (DDSketch) lhs; + union.mergeWith((DDSketch) rhs); + return union; + } + + @Override + public AggregatorFactory getCombiningFactory() + { + return new DDSketchAggregatorFactory(name, name, relativeError, numBins); + } + + @Override + public AggregatorFactory getMergingFactory(AggregatorFactory other) throws AggregatorFactoryNotMergeableException + { + if (other.getName().equals(this.getName()) && this.getClass() == other.getClass()) { + return getCombiningFactory(); + } else { + throw new AggregatorFactoryNotMergeableException(this, other); + } + } + + @Override + public List<AggregatorFactory> getRequiredColumns() + { + return Collections.singletonList( + new DDSketchAggregatorFactory( + name, + fieldName, + relativeError, + numBins + ) + ); + } + + @Override + public Object deserialize(Object serializedSketch) + { + return DDSketchUtils.deserialize(serializedSketch); + } + + @Nullable + @Override + public Object finalizeComputation(@Nullable Object object) + { + return object == null ? null : ((DDSketch) object).getCount(); + } + + @Override + @JsonProperty + public String getName() + { + return name; + } + + @JsonProperty + public String getFieldName() + { + return fieldName; + } + + @JsonProperty + public double getRelativeError() + { + return relativeError; + } + + @JsonProperty + public int getNumBins() + { + return numBins; + } + + @Override + public List<String> requiredFields() + { + return Collections.singletonList(fieldName); + } + + /** + * actual type is {@link DDSketch} + */ + @Override + public ColumnType getIntermediateType() + { + return TYPE; + } + + @Override + public ColumnType getResultType() + { + return TYPE; + } + + /* + * Each bounded lower collapsing store yields a max size of numBins * 8 bytes (size Of Double) in terms of size. + * Since the sketch contains a store for positive values and negative values, a fully filled sketch at maximum would contain: + * 2 * numBins * 8Bytes for storage. Other tracked members of the serialized sketch are constant, + * so we add 1k as buffer for these members. These members include mapping reconstruction, and zero counts. Review Comment: Ah, that was an old comment. I have updating the doc to reference the 12 descriptor bytes. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
