[jira] [Commented] (FLINK-1444) Add data properties for data sources

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

    [ https://issues.apache.org/jira/browse/FLINK-1444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14291033#comment-14291033 ] 

Robert Metzger commented on FLINK-1444:
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I've prototyped something like this here: https://github.com/rmetzger/flink/compare/local_joins
Maybe its helpful for you.

> Add data properties for data sources
> ------------------------------------
>
>                 Key: FLINK-1444
>                 URL: https://issues.apache.org/jira/browse/FLINK-1444
>             Project: Flink
>          Issue Type: New Feature
>          Components: Java API, JobManager, Optimizer
>    Affects Versions: 0.9
>            Reporter: Fabian Hueske
>            Priority: Minor
>
> This issue proposes to add support for attaching data properties to data sources. These data properties are defined with respect to input splits.
> Possible properties are:
> - partitioning across splits: all elements of the same key (combination) are contained in one split
> - sorting / grouping with splits: elements are sorted or grouped on certain keys within a split
> - key uniqueness: a certain key (combination) is unique for all elements of the data source. This property is not defined wrt. input splits.
> The optimizer can leverage this information to generate more efficient execution plans.
> The InputFormat will be responsible to generate input splits such that the promised data properties are actually in place. Otherwise, the program will produce invalid results. 



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