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Message Posted: Fri, 19 Jan 2001 @ 14:48:46 GMT


     
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Subj:   Re: Unique Value Algorithm
 
From:   David Wellman

Claybourne,

All of the OLAP functions generate the "all-AMP STAT function" step which will cause a redistribution (in fact two I think, one to distribute by value and then a second one to get it back to the correct AMP ready for the merge into the target table). This may well be a downside of using CSUM to generate sequential numbers.

However, bear in mind that the hashrow function may not generate unique values even with unique 'input' data values. I'm thinking back to your initial email on this subject. This may be especially true when you're dealing with three integers as your input columns (do they contain overlapping ranges of values - this'll just make it worse). But there again unique values may not be an absolute requirement for you.


Regards,

Dave



     
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