[teiid-issues] [JBoss JIRA] (TEIID-2549) Join planning produces cross joins with limited costing

[Steven Hawkins (JIRA)]

     [ https://issues.jboss.org/browse/TEIID-2549?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steven Hawkins closed TEIID-2549.
---------------------------------


    
> Join planning produces cross joins with limited costing
> -------------------------------------------------------
>
>                 Key: TEIID-2549
>                 URL: https://issues.jboss.org/browse/TEIID-2549
>             Project: Teiid
>          Issue Type: Bug
>          Components: Query Engine
>    Affects Versions: 7.7
>            Reporter: Steven Hawkins
>            Assignee: Steven Hawkins
>             Fix For: 8.4.1, 8.5
>
>
> The join planning logic does not gracefully handle a lack of costing information in effective cross joins (where there is still outside criteria).  For example with a small table x that only has cardinality set and a large table y with no costing information, the join structure
> from x inner join y as y1 on x.col = y1.col inner join y as y2 on x.col1 = y2.col1
> can result in a cross join plan between y1 and y2 (although the specifics of the plan may verify from version to version - in 7.7 the cross join will likely be pushed down, while in 8.4 a dependent join can be created depending upon the size of x, but can still produce a pushed cross join).

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