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Message Posted: Sat, 24 Aug 2001 @ 18:11:49 GMT


     
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Subj:   Re: Using Time(0)
 
From:   Michael Larkins

Hi Mike:

You have receive some very good CAST techniques to work around your problem. However, be aware that converting data is slow and converting converted data (CAST within a CAST) is very slow over millions of rows.

I have seen SQL generated out of Business Objects that uses this techique. It contained 2 of these. When we did date math instead, the run time went from 1 hour to 4 minutes and 47 seconds - a considerable savings.

If you are using these for comparison purposes, I would first try a correlated subquery, something like this:

WHERE < date-col > =(SELECT MAX(< date-col >) FROM < table >
             WHERE < domain-col-t1 > = < domain-col-t2 >)
AND < time-col > =(SELECT MAX(< time-col >) FROM < table >
             WHERE < domain-col-t1 > = < domain-col-t2 >)

Good luck,

Mike



     
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