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https://issues.apache.org/jira/browse/FLINK-687?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14562593#comment-14562593
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Till Rohrmann commented on FLINK-687:
-------------------------------------
How do you want to realize the outer join based on a hash join variant? Isn't
it easier to realize it as a sort merge variant? Otherwise you would have to
keep track which elements from the build side have matched to at least one
element of the probe side.
For the left/right outer join it should be possible to implement a sort merge
and hash join strategy.
> 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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