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ASF GitHub Bot logged work on BEAM-4461: ---------------------------------------- Author: ASF GitHub Bot Created on: 01/Nov/18 19:18 Start Date: 01/Nov/18 19:18 Worklog Time Spent: 10m Work Description: akedin commented on a change in pull request #6832: [BEAM-4461] CoGroup transforms for schemas. URL: https://github.com/apache/beam/pull/6832#discussion_r230143949 ########## File path: sdks/java/core/src/main/java/org/apache/beam/sdk/schemas/transforms/CoGroup.java ########## @@ -0,0 +1,326 @@ +/* + * 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.beam.sdk.schemas.transforms; + +import com.google.common.collect.ImmutableMap; +import com.google.common.collect.Lists; +import com.google.common.collect.Maps; +import java.util.Collections; +import java.util.Comparator; +import java.util.List; +import java.util.Map; +import java.util.TreeMap; +import java.util.stream.Collectors; +import javax.annotation.Nullable; +import org.apache.beam.sdk.coders.KvCoder; +import org.apache.beam.sdk.schemas.FieldAccessDescriptor; +import org.apache.beam.sdk.schemas.Schema; +import org.apache.beam.sdk.schemas.Schema.FieldType; +import org.apache.beam.sdk.schemas.SchemaCoder; +import org.apache.beam.sdk.transforms.DoFn; +import org.apache.beam.sdk.transforms.PTransform; +import org.apache.beam.sdk.transforms.ParDo; +import org.apache.beam.sdk.transforms.SerializableFunction; +import org.apache.beam.sdk.transforms.join.CoGbkResult; +import org.apache.beam.sdk.transforms.join.CoGroupByKey; +import org.apache.beam.sdk.transforms.join.KeyedPCollectionTuple; +import org.apache.beam.sdk.values.KV; +import org.apache.beam.sdk.values.PCollection; +import org.apache.beam.sdk.values.PCollectionTuple; +import org.apache.beam.sdk.values.Row; +import org.apache.beam.sdk.values.TupleTag; + +/** + * A transform that performs equijoins across multiple schema {@link PCollection}s. + * + * <p>This transform has similarites to {@link CoGroupByKey}, however works on PCollections that + * have schemas. This allows users of the transform to simply specify schema fields to join on. The + * output type of the transform is a {@literal KV<Row, Row>} where the value contains one field for + * every input PCollection and the key represents the fields that were joined on. By default the + * cross product is not expanded, so all fields in the output row are array fields. + * + * <p>For example, the following demonstrates joining three PCollections on the "user" and "country" + * fields. + * + * <pre>{@code + * TupleTag<Input1Type> input1Tag = new TupleTag<>("input1"); + * TupleTag<Input2Type> input2Tag = new TupleTag<>("input2"); + * TupleTag<Input3Type> input3Tag = new TupleTag<>("input3"); + * PCollection<KV<Row, Row>> joined = PCollectionTuple + * .of(input1Tag, input1) + * .and(input2Tag, input2) + * .and(input3Tag, input3) + * .apply(CoGroup.byFieldNames("user", "country")); + * }</pre> + * + * <p>In the above case, the key schema will contain the two string fields "user" and "country"; in + * this case, the schemas for Input1, Input2, Input3 must all have fields named "user" and + * "country". The value schema will contain three array of Row fields named "input1" "input2" and Review comment: Also I am not sure it is a right thing to put the values into rows, especially if you already use KVs and CoGBK, I would stick to CoGbkResult-style or KVs: ``` Key: Row with fields/values of Group fields: { "user" : xxxx, "country" : yyyy } Value: CoGbkResult with keys corresponding to each input tag, values are iterables of Rows for the matching Keys { KV { "input1" => [ /* rows from input1 with matching key */ ] }, KV { "input2" => [ /* rows from input 2 with matching key */ ] }, KV { "input3" => [ // rows from input 3 with matching key, e.g.: Row { "user" : xxxx, "country": yyyy, "orderId" : aaaa, "sku" : 1234 }, Row { "user" : xxxx, "country": yyyy, "orderId" : bbbb, "sku" : 5678 } ] } ``` ---------------------------------------------------------------- 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: us...@infra.apache.org Issue Time Tracking ------------------- Worklog Id: (was: 161706) Time Spent: 16h 40m (was: 16.5h) > Create a library of useful transforms that use schemas > ------------------------------------------------------ > > Key: BEAM-4461 > URL: https://issues.apache.org/jira/browse/BEAM-4461 > Project: Beam > Issue Type: Sub-task > Components: sdk-java-core > Reporter: Reuven Lax > Assignee: Reuven Lax > Priority: Major > Time Spent: 16h 40m > Remaining Estimate: 0h > > e.g. JoinBy(fields). Project, Filter, etc. -- This message was sent by Atlassian JIRA (v7.6.3#76005)