Is there a performance hit selecting rows based upon a constructed CASE column?

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Is there a performance hit selecting rows...

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TimManns

Posted 4/2/2008 5:35:59 PM

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Group: Forum Members
Last Login: Yesterday @ 3:36:10 AM
Posts: 20, Visits: 67

Hi,

Quick question. I think there is no difference, but I need to be sure.

In a SELECT or INSERT statement if I use a CASE statement to create a new column and then select rows based upon the value of that new column, is it any slower (or faster) than simply repeating the logic of the CASE statement as a direct WHERE condition?

I'm processing a *lot* of data with nasty string functions and I need every ounce of optimisation I can get :)

Thanks

Tim

Post #11127

dnoeth

Posted 4/3/2008 3:11:43 AM

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Last Login: 6/25/2008 7:26:06 AM
Posts: 474, Visits: 202

Hi Ti,
you're right, there's no difference.
Btw, if you want to lower CPU usage, stay away from conversions involving type casts from char to numeric/date and vice versa.

Dieter

Post #11128

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