[teiid-issues] [JBoss JIRA] (TEIID-2870) Expand "allow-join" extension property on Foreign Key

[Ramesh Reddy (JIRA)]

    [ https://issues.jboss.org/browse/TEIID-2870?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12948659#comment-12948659 ] 

Ramesh Reddy commented on TEIID-2870:
-------------------------------------

* Yes, CROSS is eliminated because of the capabilities of translator define the JOINs as based KEY. So this gets handled by Teiid engine
* Correct about LEFT OUTER behavior.

On RIGHT OUTER, on I have two different scenarios. Where foreign table is available 
1) only as embedded in parent's table
2) embedded in parent's table + a separate table, note the separate table may contain more rows than the embedded

In scenario (1) yes RIGHT OUTER and INNER are same. However, on the scenario (2) INNER is fine, RIGHT OUTER is not, and currently I am just throwing exception.

So, with this feature, I hope to detect that RIGHT OUTER in the last scenario during the planning phase and avoid the exception and do the processing in Teiid engine over the two separate tables.
                
> Expand "allow-join" extension property on Foreign Key
> -----------------------------------------------------
>
>                 Key: TEIID-2870
>                 URL: https://issues.jboss.org/browse/TEIID-2870
>             Project: Teiid
>          Issue Type: Enhancement
>          Components: Query Engine
>    Affects Versions: 8.7
>            Reporter: Ramesh Reddy
>            Assignee: Steven Hawkins
>
> Currently "allow-join" property on a Foreign Key, defines if the joins based on that Foreign Key that are valid to push to the source or not, when JOIN capability is turned on at translator level. This feature is used in the MongoDB translator to allow JOINS to pushed to source.
> What I have seen is "allow-join" is blanket capability that says it supports all LEFT, RIGHT, INNER and CROSS JOINS.  It is useful to define this capability in fine grained manner to allow each kind of JOIN explicitly to control the JOIN behavior.
> The need came from MongoDB translator, where INNER,LEFT are possible but CROSS and RIGHT are not.

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