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https://issues.apache.org/jira/browse/BEAM-4461?focusedWorklogId=162833&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-162833
]
ASF GitHub Bot logged work on BEAM-4461:
----------------------------------------
Author: ASF GitHub Bot
Created on: 06/Nov/18 01:24
Start Date: 06/Nov/18 01:24
Worklog Time Spent: 10m
Work Description: reuvenlax commented on a change in pull request #6832:
[BEAM-4461] CoGroup transforms for schemas.
URL: https://github.com/apache/beam/pull/6832#discussion_r230973653
##########
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:
Added a more detailed comment (though I used Java POJOs to illustrate the
schema).
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Issue Time Tracking
-------------------
Worklog Id: (was: 162833)
Time Spent: 17h (was: 16h 50m)
> 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: 17h
> Remaining Estimate: 0h
>
> e.g. JoinBy(fields). Project, Filter, etc.
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