AlexanderSaydakov commented on a change in pull request #5712: HllSketch module URL: https://github.com/apache/incubator-druid/pull/5712#discussion_r218159965
########## File path: extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/hll/HllSketchBuildAggregatorFactory.java ########## @@ -0,0 +1,91 @@ +/* + * 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.datasketches.hll; + +import javax.annotation.Nullable; + +import com.fasterxml.jackson.annotation.JsonCreator; +import com.fasterxml.jackson.annotation.JsonProperty; +import com.yahoo.sketches.hll.HllSketch; +import com.yahoo.sketches.hll.TgtHllType; + +import org.apache.druid.query.aggregation.Aggregator; +import org.apache.druid.query.aggregation.AggregatorUtil; +import org.apache.druid.query.aggregation.BufferAggregator; +import org.apache.druid.segment.ColumnSelectorFactory; +import org.apache.druid.segment.ColumnValueSelector; + +/** + * This aggregator factory is for building sketches from raw data. + * The input column can contain identifiers of type string, char[], byte[] or any numeric type. + * @author Alexander Saydakov + */ +public class HllSketchBuildAggregatorFactory extends HllSketchAggregatorFactory +{ + + @JsonCreator + public HllSketchBuildAggregatorFactory( + @JsonProperty("name") final String name, + @JsonProperty("fieldName") final String fieldName, + @JsonProperty("lgK") @Nullable final Integer lgK, + @JsonProperty("tgtHllType") @Nullable final String tgtHllType) + { + super(name, fieldName, lgK, tgtHllType); + } + + @Override + public String getTypeName() + { + return HllSketchModule.BUILD_TYPE_NAME; + } + + @Override + protected byte getCacheTypeId() + { + return AggregatorUtil.HLL_SKETCH_BUILD_CACHE_TYPE_ID; + } + + @Override + public Aggregator factorize(final ColumnSelectorFactory columnSelectorFactory) + { + final ColumnValueSelector<Object> selector = columnSelectorFactory.makeColumnValueSelector(getFieldName()); + return new HllSketchBuildAggregator(selector, getLgK(), TgtHllType.valueOf(getTgtHllType())); + } + + @Override + public BufferAggregator factorizeBuffered(final ColumnSelectorFactory columnSelectorFactory) + { + final ColumnValueSelector<Object> selector = columnSelectorFactory.makeColumnValueSelector(getFieldName()); + return new HllSketchBuildBufferAggregator( + selector, + getLgK(), + TgtHllType.valueOf(getTgtHllType()), + getMaxIntermediateSize() + ); + } + + // for the HLL_4 sketch type, this value can be exceeded slightly in extremely rare cases Review comment: The sketch will move from the buffer to heap. I will mention this. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
