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From "Chiwan Park (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-687) Add support for outer-joins
Date Wed, 27 May 2015 14:00:41 GMT

    [ https://issues.apache.org/jira/browse/FLINK-687?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14561009#comment-14561009

Chiwan Park commented on FLINK-687:

Yes. Splitting this issue into two sub issues is reasonable. :)

I think the outer join algorithm based HashJoin should implemented a class extending {{HashMatchIteratorBase}}
and implementing JoinTaskIterator. Is it right?

I have another question. There are many match iterators in {{org.apache.flink.runtime.operators.hash}}
package. I know the difference between {{First}} and {{Second}} but don't know the difference
{{Reusing}} and {{NonReusing}} and the meaning of {{ReOpenable}}. Could you explain me about
this keyword?

If my approach is wrong, please advise me.
Thank you :)

> Add support for outer-joins
> ---------------------------
>                 Key: FLINK-687
>                 URL: https://issues.apache.org/jira/browse/FLINK-687
>             Project: Flink
>          Issue Type: New Feature
>            Reporter: GitHub Import
>            Assignee: Chiwan Park
>            Priority: Minor
>              Labels: github-import
>             Fix For: pre-apache
> There are three types of outer-joins:
> - left outer,
> - right outer, and
> - full outer
> joins.
> An outer-join does not "filter" tuples of the outer-side that do not find a matching
tuple on the other side. Instead, it is joined with a NULL value.
> Supporting outer-joins requires some modifications in the join execution strategies.
> ---------------- Imported from GitHub ----------------
> Url: https://github.com/stratosphere/stratosphere/issues/687
> Created by: [fhueske|https://github.com/fhueske]
> Labels: enhancement, java api, runtime, 
> Created at: Mon Apr 14 12:09:00 CEST 2014
> State: open

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