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Message Posted: Mon, 15 Mar 2004 @ 17:27:16 GMT


     
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Subj:   Re: Odd explain plan in a query using MINUS
 
From:   David Wellman

John,

I've seen the same things with UNION. (I think) What's happening is that Teradata is hashing the entire row and distributing based on that hash, then looking within the set of rows with same rowhash for duplicates in order to do the MINUS function. "It ain't pretty" and it could be done another way, but I think you'll find that is what is happening.


Cheers,

Dave

Ward Analytics Ltd: Information in motion (www.ward-analytics.com)



     
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