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Message Posted: Mon, 13 Nov 2006 @ 09:38:35 GMT


     
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Subj:   Questions on Nested Joins
 
From:   Weng, Silei

Hi Everyone,

I have some questions about the Nested Joins.

Does the Nested Join only occur in the inner join? If not, could anyone kindly explain how to make a nested join in the left join? (NUSI? Table size?)

As it says:" the right table in the nested join step MUST have a NUSI and there must be a join term or terms which cover that NUSI. The left table in the nested join MUST be duplicated on all amps. This is because NUSIs are not hash distributed. They are local." - <Process for Analyzing Problem Queries> written by Glen K. Blood; from the white papers of the TD forum library.

So what if I have a USI instead of the NUSI? What is the condition to have a nested join on a USI column? Does the left table still need to be duplicated?

Thanks a lot in advance!


Regards,

Silei



     
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