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https://issues.apache.org/jira/browse/FLINK-991?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14057360#comment-14057360
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Fabian Hueske commented on FLINK-991:
-------------------------------------
Both will actually work.
Referring to the member of a POJO by its name to identify a grouping key will
work in most cases I believe.
However in cases where a more complex key needs to be constructed, a
{{KeySelector}} function might still be necessary.
I suggest to update the Wordcount examples with the new syntax. However, we
might think about a case where we can show how a {{KeySelector}} function
works.
It makes probably sense to discuss all ways to specify keys in isolation from
Reduce, Join, and CoGroup. Otherwise this stuff will be replicated a lot.
> Add documentation for POJO expression keys
> ------------------------------------------
>
> Key: FLINK-991
> URL: https://issues.apache.org/jira/browse/FLINK-991
> Project: Flink
> Issue Type: Bug
> Components: Documentation, Java API
> Affects Versions: 0.6-incubating
> Reporter: Fabian Hueske
> Assignee: Mariem Ayadi
> Labels: starter
>
> The Java API documentation needs to be extended to reflect the extensions
> added by FLINK-908.
> These are basically expression keys for POJO objects, i.e., selecting public
> fields of POJOs as keys by their names.
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