[teiid-issues] [JBoss JIRA] Resolved: (TEIID-1272) Join planning should make better decisions when mixing costing and unknown values

Wed Sep 22 17:29:28 EDT 2010

     [ https://jira.jboss.org/browse/TEIID-1272?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steven Hawkins resolved TEIID-1272.
-----------------------------------

    Resolution: Done

updated the join ordering logic to better use the known side cost when determining the join order.  I did not change the base join costing logic as that could lead to bad dependent join logic (but there still is room for improvement).

> Join planning should make better decisions when mixing costing and unknown values
> ---------------------------------------------------------------------------------
>
>                 Key: TEIID-1272
>                 URL: https://jira.jboss.org/browse/TEIID-1272
>             Project: Teiid
>          Issue Type: Quality Risk
>          Components: Query Engine
>    Affects Versions: 7.0
>            Reporter: Steven Hawkins
>            Assignee: Steven Hawkins
>             Fix For: 7.1.1
>
>
> When faced with an unknown value during join planning we use the default assumption of 100000 rows.  However this may cause non-performant cross joins to be pushed in the worst case.  It would be better to either not cost these scenarios or get a more accurate estimate of the post join cardinality based upon the the other side of the join.

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