[jira] [Commented] (KAFKA-4218) Enable access to key in ValueTransformer

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-4218?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16099491#comment-16099491 ] 

ASF GitHub Bot commented on KAFKA-4218:
---------------------------------------

GitHub user jeyhunkarimov opened a pull request:

    https://github.com/apache/kafka/pull/3570

    KAFKA-4218: KIP-149, Enabling withKey interfaces in streams

    This PR aims to provide key access to ValueMapper, ValueJoiner, ValueTransformer, Initializer and Reducer interfaces. More details can be found in [here](https://cwiki.apache.org/confluence/display/KAFKA/KIP-149%3A+Enabling+key+access+in+ValueTransformer%2C+ValueMapper%2C+and+ValueJoiner)

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/jeyhunkarimov/kafka KIP-149

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/kafka/pull/3570.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #3570
    
----
commit a1bbfdca86c53359ef75217ec4aaad06179d967d
Author: Jeyhun Karimov <je...@gmail.com>
Date:   2017-07-21T23:18:05Z

    Add withKey methods to KStream, KGroupedStream, KTable and KGroupedTable interfaces

----


> Enable access to key in ValueTransformer
> ----------------------------------------
>
>                 Key: KAFKA-4218
>                 URL: https://issues.apache.org/jira/browse/KAFKA-4218
>             Project: Kafka
>          Issue Type: Improvement
>          Components: streams
>    Affects Versions: 0.10.0.1
>            Reporter: Elias Levy
>            Assignee: Jeyhun Karimov
>              Labels: api, kip
>             Fix For: 1.0.0
>
>
> While transforming values via {{KStream.transformValues}} and {{ValueTransformer}}, the key associated with the value may be needed, even if it is not changed.  For instance, it may be used to access stores.  
> As of now, the key is not available within these methods and interfaces, leading to the use of {{KStream.transform}} and {{Transformer}}, and the unnecessary creation of new {{KeyValue}} objects.
> KIP-149: https://cwiki.apache.org/confluence/display/KAFKA/KIP-149%3A+Enabling+key+access+in+ValueTransformer%2C+ValueMapper%2C+and+ValueJoiner



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