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https://issues.apache.org/jira/browse/FLINK-1267?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17321780#comment-17321780
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Flink Jira Bot commented on FLINK-1267:
---------------------------------------
This issue and all of its Sub-Tasks have not been updated for 180 days. So, it
has been labeled "stale-minor". If you are still affected by this bug or are
still interested in this issue, please give an update and remove the label. In
7 days the issue will be closed automatically.
> Add crossGroup operator
> -----------------------
>
> Key: FLINK-1267
> URL: https://issues.apache.org/jira/browse/FLINK-1267
> Project: Flink
> Issue Type: New Feature
> Components: API / DataSet, Runtime / Task
> Affects Versions: 0.7.0-incubating
> Reporter: Fabian Hueske
> Assignee: pietro pinoli
> Priority: Minor
> Labels: stale-minor
>
> A common operator is to pair-wise compare or combine all elements of a group
> (there were two questions about this on the user mailing list, recently).
> Right now, this can be done in two ways:
> 1. {{groupReduce}}: consume and store the complete iterator in memory and
> build all pairs
> 2. do a self-{{Join}}: the engine builds all pairs of the full symmetric
> Cartesian product.
> Both approaches have drawbacks. The {{groupReduce}} variant requires that the
> full group fits into memory and is more cumbersome to implement for the user,
> but pairs can be arbitrarily built. The self-{{Join}} approach pushes most of
> the work into the system, but the execution strategy does not treat the
> self-join different from a regular join (both identical inputs are shuffled,
> etc.) and always builds the full symmetric Cartesian product.
> I propose to add a dedicated {{crossGroup()}} operator, that offers this
> functionality in a proper way.
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