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From "Fabian Hueske (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-687) Add support for outer-joins
Date Wed, 27 May 2015 12:44:18 GMT

    [ https://issues.apache.org/jira/browse/FLINK-687?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14560892#comment-14560892

Fabian Hueske commented on FLINK-687:

Hi [~chiwanpark], this would be a great addition to Flink!
Although, this is not an easy thing I am confident that we can do it :-)

Adding outer joins touches many parts of the system's core:

- Join Algorithms
- Execution strategies
- Optimizer

I would suggest to split this issue into at least two sub-issues. 

1. implement a HashJoin based join algorithm for left/right outer joins (no full outer join
yet) and back it by unit tests.
2. add outer joins to the API, go through the optimizer, and finally configure the correct
runtime code. 

Maybe this issue can be broken down even further.

What do you think?

> 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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