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Message Posted: Wed, 26 Apr 2006 @ 18:02:37 GMT

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Subj:   Re: Index Mechanism?
From:   Victor Sokovin

  In the first case value of Col1 will be used while inserting and pulling the data from AMPs. But how exactly the Indexing will work in the second case? Is it the case that the combination of Col1 and Col2 will be HASHED and then that hash value is used to insert or pull data from database?  

Dieter once spilled the beans:

www.teradataforum.com/teradata/20040108_162008.htm .

I can appreciate the commutativity part: PI(A, B) = PI(B, A).

But what is the importance of the second part,

     Hash (A) * Hash (B) + Hash (A) + Hash (B) =
     Hash (B) * Hash (A) + Hash (B) + Hash (A) ?

I hope this new take on composite PI will help me understand this.


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