johnedmonds commented on a change in pull request #13889: URL: https://github.com/apache/beam/pull/13889#discussion_r574079122
########## File path: sdks/go/pkg/beam/transforms/stats/quantiles.go ########## @@ -0,0 +1,710 @@ +// 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 stats + +// Approximate quantiles is implemented based on https://arxiv.org/pdf/1907.00236.pdf. + +import ( + "bytes" + "container/heap" + "context" + "encoding/gob" + "encoding/json" + "hash/crc32" + "io" + "math" + "reflect" + "sort" + + "github.com/apache/beam/sdks/go/pkg/beam" + "github.com/apache/beam/sdks/go/pkg/beam/core/util/reflectx" +) + +func init() { + compactorsType := reflect.TypeOf((**compactors)(nil)).Elem() + weightedElementType := reflect.TypeOf((*weightedElement)(nil)).Elem() + beam.RegisterType(compactorsType) + beam.RegisterType(weightedElementType) + beam.RegisterType(reflect.TypeOf((*approximateQuantilesInputFn)(nil)).Elem()) + beam.RegisterType(reflect.TypeOf((*approximateQuantilesMergeOnlyFn)(nil)).Elem()) + beam.RegisterType(reflect.TypeOf((*approximateQuantilesOutputFn)(nil)).Elem()) + beam.RegisterType(reflect.TypeOf((*shardElementsFn)(nil)).Elem()) + beam.RegisterCoder(compactorsType, encodeCompactors, decodeCompactors) + beam.RegisterCoder(weightedElementType, encodeWeightedElement, decodeWeightedElement) +} + +// Opts contains settings used to configure how approximate quantiles are computed. +type Opts struct { + // Controls the memory used and approximation error (difference between the quantile returned and the true quantile.) + K int + // Number of quantiles to return. The algorithm will return NumQuantiles - 1 numbers + NumQuantiles int + // For extremely large datasets, runners may have issues with out of memory errors or taking too long to finish. + // If ApproximateQuantiles is failing, you can use this option to tune how the data is sharded internally. + // This parameter is optional. If unspecified, Beam will compact all elements into a single compactor at once using a single machine. Review comment: I've added an example. Hopefully this makes sense. ---------------------------------------------------------------- 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: [email protected]
