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Message Posted: Tue, 22 Jun 2004 @ 13:32:45 GMT


     
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Subj:   Re: Will the Hash value change?
 
From:   Michael Larkins

Nazy:

The Row hash for character columns of different lengths are the same. This can be seen in the following that compares a char(10) with a char(6400):

     sel 'they match'
     where hashrow('abc'(char(10)))=hashrow('abc'(char(6400)))

The true concern of comparing columns of different lengths is one of conversation. In other words, every time these columns are joined together (compared), the shorter one must be expanded to match the length of the longer one. Although this is done automatically, if it happens often it can negatively impact your CPU utilization and most likely your overall system performance as a result.


Hope this helps,

Michael Larkins
Certified Teradata Master



     
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