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Message Posted: Fri, 09 Jul 1999 @ 18:00:55 GMT


     
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Subj:   Re: Product and Merge Joins
 
From:   Hays McLean

Thanks for the responses. In these two queries, I know they are not logically equivalent, but I also know that the nested query would not contain any (or very few as to be meaningless) of the conditions that I am excluding. However, it seems to be good to add the (irrelevant) exclusions in order to get the optimizer to use a merge join method instead of a product join to save much time.

By experimenting, I have found that I can add a number of bogus exclusions to the nested query and apparently "trick" the optimizer into doing a merge join rather than a product join. This way the query results come in much, much faster. Is there any way besides this to force the system to use one join method over another?


Hays McLean
First American National Bank



     
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