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From "Mamta A. Satoor (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-855) Document optimizer overrides which were introduced in 10.2
Date Thu, 09 Feb 2006 03:50:07 GMT
    [ http://issues.apache.org/jira/browse/DERBY-855?page=comments#action_12365685 ] 

Mamta A. Satoor commented on DERBY-855:
---------------------------------------

Eric, I hope this is the last piece of information I will have to request you to change. After
getting input from Jeff Lichtman and Satheesh Bandaram on joinStrategy, we should change "The
joinStrategy property can be used only within a TableExpression, but it must be used in conjunction
with the joinOrder property. Do not let the optimizer choose the join order." so that using
joinOrder along with joinStrategy is not an absolute rule but is recommended. Let me copy
what Jeff said on this issue "I think this should be stated as a piece of advice, not as an
absolute rule. Generally, specifying a join strategy doesn't make much sense unless you already
know the join order. That is, the same join strategy wouldn't necessarily be optimal for different
join orders. But specifying the join strategy without specifying the join order won't prevent
the query from running (except perhaps in some corner cases), nor will it cause the query
to return the wrong results."



> Document optimizer overrides which were introduced in 10.2
> ----------------------------------------------------------
>
>          Key: DERBY-855
>          URL: http://issues.apache.org/jira/browse/DERBY-855
>      Project: Derby
>         Type: Sub-task
>   Components: Documentation
>     Versions: 10.2.0.0
>     Reporter: Mamta A. Satoor
>     Assignee: Eric Radzinski
>      Fix For: 10.2.0.0
>  Attachments: ctundepthoptover.html, ctunoptimzoverride.html, ctunoptimzoverride.html,
derby855-2.diff, derby855.diff, derby855_html_files.zip, tuning_guide.zip
>
> Optimizer overrides support in Derby was added as jira entry DERBY-573. Eric Radzinski
is working on the documentation part of the feature. This issue is to keep track of documentation
changes.

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