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Posted to commits@beam.apache.org by "Aljoscha Krettek (JIRA)" <ji...@apache.org> on 2016/09/20 20:30:22 UTC

[jira] [Commented] (BEAM-638) Add a Window function to create a bounded PCollection from an unbounded one

    [ https://issues.apache.org/jira/browse/BEAM-638?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15507706#comment-15507706 ] 

Aljoscha Krettek commented on BEAM-638:
---------------------------------------

I don't think it's possible to provide such a function.

What would the semantics of such a function be? That is, when would it consider that window "done", what happens to the computation upstream from that function/transformation, would it be canceled? Also, which window would be the one window that we take, for example from {{FixedWindows}}?

> Add a Window function to create a bounded PCollection from an unbounded one
> ---------------------------------------------------------------------------
>
>                 Key: BEAM-638
>                 URL: https://issues.apache.org/jira/browse/BEAM-638
>             Project: Beam
>          Issue Type: New Feature
>          Components: sdk-java-core
>            Reporter: Jean-Baptiste Onofré
>            Assignee: Davor Bonaci
>
> Today, if the pipeline source is unbounded, and the sink expects a bounded collection, there's no way to use a single pipeline. Even a window creates a chunk on the unbounded PCollection, but the "sub" PCollection is still unbounded.
> It would be helpful for users to have a Window function that create a bounded PCollection (on the window) from an unbounded PCollection coming from the source.



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