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https://issues.apache.org/jira/browse/FLINK-703?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14502995#comment-14502995
]
ASF GitHub Bot commented on FLINK-703:
--------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/572#discussion_r28696843
--- Diff:
flink-tests/src/test/java/org/apache/flink/test/javaApiOperators/GroupReduceITCase.java
---
@@ -1063,6 +1065,33 @@ public void reduce(Iterable<Tuple5<Integer, Long,
Integer, String, Long>> values
}
+ @Test
+ public void testGroupReduceWithAtomicValue() throws Exception {
+ final ExecutionEnvironment env =
ExecutionEnvironment.getExecutionEnvironment();
+ DataSet<Integer> ds = env.fromElements(1, 1, 2, 3, 4);
+ DataSet<Integer> reduceDs = ds.groupBy("*").reduceGroup(new
GroupReduceFunction<Integer, Integer>() {
+ @Override
+ public void reduce(Iterable<Integer> values,
Collector<Integer> out) throws Exception {
+ Set<Integer> set = new HashSet<Integer>();
--- End diff --
Since all elements of a group are identical when you do `groupBy("*")` this
could be implemented a bit easier by just returning the first element of a
group (`out.collect(values.iterator().next())`).
> Use complete element as join key.
> ---------------------------------
>
> Key: FLINK-703
> URL: https://issues.apache.org/jira/browse/FLINK-703
> Project: Flink
> Issue Type: Improvement
> Reporter: GitHub Import
> Assignee: Chiwan Park
> Priority: Trivial
> Labels: github-import
> Fix For: pre-apache
>
>
> In some situations such as semi-joins it could make sense to use a complete
> element as join key.
> Currently this can be done using a key-selector function, but we could offer
> a shortcut for that.
> This is not an urgent issue, but might be helpful.
> ---------------- Imported from GitHub ----------------
> Url: https://github.com/stratosphere/stratosphere/issues/703
> Created by: [fhueske|https://github.com/fhueske]
> Labels: enhancement, java api, user satisfaction,
> Milestone: Release 0.6 (unplanned)
> Created at: Thu Apr 17 23:40:00 CEST 2014
> State: open
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