[jira] [Commented] (FLINK-553) Add getGroupKey() method to group-at-time operators

["Robert Metzger (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-553?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14172208#comment-14172208 ] 

Robert Metzger commented on FLINK-553:
--------------------------------------

Is there anybody else interested in picking up this issue?

I personally think that this is a big disadvantage of our current API. I understand that our data model is more powerful and that it is probably impossible to solve this issue in a typesafe manner. But you almost always want to use the key in the grouping operation.

> Add getGroupKey() method to group-at-time operators
> ---------------------------------------------------
>
>                 Key: FLINK-553
>                 URL: https://issues.apache.org/jira/browse/FLINK-553
>             Project: Flink
>          Issue Type: Improvement
>          Components: Java API, Scala API
>            Reporter: GitHub Import
>              Labels: github-import
>             Fix For: pre-apache
>
>
> Group-at-a-time operators (Reduce & CoGroup) work on multiple records in one UDF call. Often these UDFs need to access the key that is common to all records of a group.
> We could add a function to set a the key of a group before the UDF is called (``setGroupKey()``) and a function to get the key (``getGroupKey()``) that can be called from the UDF.
> What do you think about this?
> ---------------- Imported from GitHub ----------------
> Url: https://github.com/stratosphere/stratosphere/issues/553
> Created by: [fhueske|https://github.com/fhueske]
> Labels: enhancement, java api, scala api, user satisfaction, 
> Assignee: [aalexandrov|https://github.com/aalexandrov]
> Created at: Mon Mar 10 22:28:27 CET 2014
> State: open



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