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https://issues.apache.org/jira/browse/BEAM-7700?focusedWorklogId=282486&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-282486
]
ASF GitHub Bot logged work on BEAM-7700:
----------------------------------------
Author: ASF GitHub Bot
Created on: 25/Jul/19 06:51
Start Date: 25/Jul/19 06:51
Worklog Time Spent: 10m
Work Description: robinyqiu commented on pull request #9129: [BEAM-7700]
Java transform catalog
URL: https://github.com/apache/beam/pull/9129#discussion_r307129477
##########
File path:
website/src/documentation/transforms/java/aggregation/cogroupbykey.md
##########
@@ -0,0 +1,73 @@
+---
+layout: section
+title: "CoGroupByKey"
+permalink: /documentation/transforms/java/aggregation/cogroupbykey/
+section_menu: section-menu/documentation.html
+---
+<!--
+Licensed 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.
+-->
+# CoGroupByKey
+<table align="left">
+ <a target="_blank" class="button"
+
href="https://beam.apache.org/releases/javadoc/current/index.html?org/apache/beam/sdk/transforms/join/CoGroupByKey.html";>
+ <img src="https://beam.apache.org/images/logos/sdks/java.png";
width="20px" height="20px"
+ alt="Javadoc" />
+ Javadoc
+ </a>
+</table>
+<br>
+Aggregates all input elements by their key and allows downstream processing
+to consume all values associated with the key. While `GroupByKey` performs
+this operation over a single input collection and thus a single type of
+input values, `CoGroupByKey` operates over multiple input collections. As
+a result, the result for each key is a tuple of the values associated with
+that key in each input collection.
+
+See more information in the [Beam Programming Guide]({{ site.baseurl
}}/documentation/programming-guide/#cogroupbykey).
+
+## Examples
+**Example**: Say you have two different files with user data; one file has
+names and email addresses and the other file has names and phone numbers.
+
+You can join those two data sets, using the username as a common key and the
+other data as the associated values. After the join, you have one data set
+that contains all of the information (email addresses and phone numbers)
+associated with each name.
+
+```java
+PCollection<KV<UID, Integer>> pt1 = /* ... */;
+PCollection<KV<UID, String>> pt2 = /* ... */;
+
+final TupleTag<Integer> t1 = new TupleTag<>();
+final TupleTag<String> t2 = new TupleTag<>();
+PCollection<KV<UID, CoGBKResult>> result =
+ KeyedPCollectionTuple.of(t1, pt1).and(t2, pt2)
+ .apply(CoGroupByKey.create());
+result.apply(ParDo.of(new DoFn<KV<K, CoGbkResult>, /* some result */>() {
+ @ProcessElement
+ public void processElement(ProcessContext c) {
+ KV<K, CoGbkResult> e = c.element();
+ CoGbkResult result = e.getValue();
+ // Retrieve all integers associated with this key from pt1
+ Iterable<Integer> allIntegers = result.getAll(t1);
+ // Retrieve the string associated with this key from pt2.
+ // Note: This will fail if multiple values had the same key in pt2.
+ String string = e.getOnly(t2);
+ ...
+}));
+```
+
+## Related transforms
+* [CombineWithContext]({{ site.baseurl
}}/documentation/transforms/java/aggregation/combinewithcontext) to combine
elements.
Review comment:
This doesn't seem related.
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Issue Time Tracking
-------------------
Worklog Id: (was: 282486)
Time Spent: 3h 20m (was: 3h 10m)
> Java transform catalog
> ----------------------
>
> Key: BEAM-7700
> URL: https://issues.apache.org/jira/browse/BEAM-7700
> Project: Beam
> Issue Type: Improvement
> Components: website
> Reporter: Rose Nguyen
> Assignee: Rose Nguyen
> Priority: Minor
> Time Spent: 3h 20m
> Remaining Estimate: 0h
>
> Create catalog of core transforms (Java)
> -Java transforms overview
> -Links to Javadocs
> -Brief description
> -Related transforms
> -Links to programming guide
> -Examples section to integrate Colab notebooks
>
> See BEAM-7464 for Python.
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