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Message Posted: Sat, 15 Dec 2001 @ 12:59:48 GMT


     
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Subj:   Re: Exists/Not Exists versus IN/Not IN
 
From:   Dieter Nöth

  Which is usually faster, using exists/not exists or in/not. And in general why.  



There's almost no difference in Teradata between IN and EXISTS, just EXPLAIN both, it's the same plan.

EXISTS/NOT EXISTS will produce the same plan, the only difference is the join type: Inclusion vs. exclusion.

IN/NOT IN will produce totally different plans, if the joined columns are NULLable, because the optimizer has to consider the three-way logic of NOT IN.

So in most cases it's better to use NOT EXISTS, especially because you don't have to think about NULLs.


Dieter



     
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