[jira] [Commented] (FLINK-3761) Introduce key group state backend

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

    [ https://issues.apache.org/jira/browse/FLINK-3761?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15288820#comment-15288820 ] 

ASF GitHub Bot commented on FLINK-3761:
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Github user gyfora commented on the pull request:

    https://github.com/apache/flink/pull/1988#issuecomment-219999205
  
    So if I understand currently there is no way to scale jobs with non-partitioned states. This also means that window operations (that register timers) will not be scalable right? 


> Introduce key group state backend
> ---------------------------------
>
>                 Key: FLINK-3761
>                 URL: https://issues.apache.org/jira/browse/FLINK-3761
>             Project: Flink
>          Issue Type: Sub-task
>          Components: state backends
>            Reporter: Till Rohrmann
>            Assignee: Till Rohrmann
>
> After an off-line discussion with [~aljoscha], we came to the conclusion that it would be beneficial to reflect the differences between a keyed and a non-keyed stream also in the state backends. A state backend which is used for a keyed stream offers a value, list, folding and value state and has to group its keys into key groups. 
> A state backend for non-keyed streams can only offer a union state to make it work with dynamic scaling. A union state is a state which is broadcasted to all tasks in case of a recovery. The state backends can then select what information they need to recover from the whole state (formerly distributed).



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