[teiid-issues] [JBoss JIRA] Commented: (TEIID-1335) Customer requesting the ability to make query planner always create dependent joins.

Fri Oct 29 12:32:54 EDT 2010

    [ https://jira.jboss.org/browse/TEIID-1335?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12560330#action_12560330 ] 

Steven Hawkins commented on TEIID-1335:
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I would rather see this as a costing or cost tuning issue.  We have some built-in assumptions about source performance when issuing the dependent side queries that may not match their particular performance characteristics.  If they can provide us with examples including costing information, if keys are used, sample timings, etc. then I can look at changing the assumptions or adding tuning parameters to the translator properties. 

> Customer requesting the ability to make query planner always create dependent joins.
> ------------------------------------------------------------------------------------
>
>                 Key: TEIID-1335
>                 URL: https://jira.jboss.org/browse/TEIID-1335
>             Project: Teiid
>          Issue Type: Feature Request
>          Components: Server
>            Reporter: Debbie Steigner
>            Assignee: Steven Hawkins
>
> Customer is finding that the query planner often chooses to use a non-dependent join plan, even when cost statistics have been gathered on all source systems and a dependent plan would perform much better.
> I've showed them how to use option makedep to force a dependent join scenario. However, it requires careful analysis of each query to setup the proper makedep parameters, and may not be feasible when working with hibernate as the client.
> Thus, they ask: is there any way to tell the query planner to always use dependent join for every join, no matter what.

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