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From "Fabian Hueske (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-925) Support KeySelector function returning Tuples
Date Thu, 03 Jul 2014 08:45:26 GMT

    [ https://issues.apache.org/jira/browse/FLINK-925?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14051200#comment-14051200

Fabian Hueske commented on FLINK-925:

Nice! Adding test cases is usually a good idea. Most of the TupleTypeComparator methods should
be easy to test. For the {{createComparator()}} method  have a look at the {{TupleComparatorTestBase}}.

>From what I have seen you should open a PR once you're done with that.

> Support KeySelector function returning Tuples
> ---------------------------------------------
>                 Key: FLINK-925
>                 URL: https://issues.apache.org/jira/browse/FLINK-925
>             Project: Flink
>          Issue Type: Improvement
>    Affects Versions: 0.6-incubating
>            Reporter: Fabian Hueske
>            Assignee: Tobias
>            Priority: Minor
>              Labels: starter
> KeySelector functions are used to extract keys on which DataSets can be grouped or joined.
> Currently, the keys types returned by KeySelector function are restricted to be comparable.
However, Flinks Tuple data types are not comparable (because this depends on the types of
its fields) which makes grouping and joining on composite keys difficult.
> We should change the signature of the groupBy(), join(), and coGroup() methods to allow
also non-comparable keys as return types of a KeySelector function. 
> Instead we will check at optimization time whether the returned type is comparable (which
is true for tuples if all elements are comparable).

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