abhishekagarwal87 commented on code in PR #13819: URL: https://github.com/apache/druid/pull/13819#discussion_r1115255614
########## extensions-core/datasketches/src/main/java/org/apache/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchConstantPostAggregator.java: ########## @@ -0,0 +1,156 @@ +/* + * 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.tuple; + +import com.fasterxml.jackson.annotation.JsonCreator; +import com.fasterxml.jackson.annotation.JsonProperty; +import com.google.common.base.Preconditions; +import org.apache.commons.codec.digest.DigestUtils; +import org.apache.datasketches.tuple.arrayofdoubles.ArrayOfDoublesSketch; +import org.apache.datasketches.tuple.arrayofdoubles.ArrayOfDoublesSketches; +import org.apache.druid.java.util.common.StringUtils; +import org.apache.druid.java.util.common.guava.Comparators; +import org.apache.druid.query.aggregation.AggregatorFactory; +import org.apache.druid.query.aggregation.AggregatorUtil; +import org.apache.druid.query.cache.CacheKeyBuilder; +import org.apache.druid.segment.data.SafeWritableMemory; + +import java.util.Collections; +import java.util.Comparator; +import java.util.Map; +import java.util.Set; + +/** + * This post-aggregator converts a given Base64 encoded string to an ArrayOfDoublesSketch. + * The input column contains name of post-aggregator output and base64 encoded input string. + * The output is a deserialized {@link ArrayOfDoublesSketch} . + */ +public class ArrayOfDoublesSketchConstantPostAggregator extends ArrayOfDoublesSketchPostAggregator +{ + + private final String value; + private final ArrayOfDoublesSketch sketchValue; + + @JsonCreator + public ArrayOfDoublesSketchConstantPostAggregator(@JsonProperty("name") String name, @JsonProperty("value") String value) + { + super(name); + Preconditions.checkArgument(value != null && !value.isEmpty(), + "Constant value cannot be null or empty, expecting base64 encoded sketch string"); + this.value = value; + this.sketchValue = deserializeSafe(value); Review Comment: you could just call `deserializeFromBase64EncodedStringSafe` and remove `deserializeSafe` ########## docs/development/extensions-core/datasketches-tuple.md: ########## @@ -207,3 +207,39 @@ Returns a human-readable summary of a given ArrayOfDoublesSketch. This is a stri "field" : <post aggregator that refers to an ArrayOfDoublesSketch (fieldAccess or another post aggregator)> } ``` + + +### Constant ArrayOfDoublesSketch + +This post aggregator adds a Base64-encoded constant ArrayOfDoublesSketch value that you can use in other post aggregators. +```json +{ + "type": "arrayOfDoublesSketchConstant", + "name": DESTINATION_COLUMN_NAME, + "value": CONSTANT_SKETCH_VALUE +} +``` + +### Base64 output of ArrayOfDoublesSketch + +This post aggregator outputs an ArrayOfDoublesSketch as a Base64-encoded string storing the constant tuple sketch value that you can use in other post aggregators. + +```json +{ + "type": "arrayOfDoublesSketchToBase64String", + "name": DESTINATION_COLUMN_NAME, + "field": <post aggregator that refers to a ArrayOfDoublesSketch (fieldAccess or another post aggregator)> +} +``` + +### Estimated metrics values for each column of ArrayOfDoublesSketch + +This post aggregator returns a list of estimated values(sum) from a given ArrayOfDoublesSketch. The result is _N_ double values, where _N_ is the number of double values kept in the sketch per key. Review Comment: is `arrayOfDoublesSketchToMetricsSumEstimate` a better name for this? -- 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]
