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Archives of the TeradataForum
Message Posted: Thu, 08 Jan 2004 @ 16:20:08 GMT
| Subj: | | Re: How to know how the hashing algorithm works |
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| From: | | Dieter Noeth |
John Adams wrote:
| | I've gotten curious about the hashing algorithm, but there's not a lot in the documentation about how it works. I'm not interested in the
proprietary details of how a value is hashed, but I am curious about how multi-field index values are determined from the values of the individual
fields. | |
| | Any guidance on this out there? | |
According to the Physical Implementation training: The hashing algorithm uses multiplication and addition as commutative operators for
handling a multi-column index.
PI(A, B) = PI(B, A)
Hash (A) * Hash (B) + Hash (A) + Hash (B) =
Hash (B) * Hash (A) + Hash (B) + Hash (A)
Dieter
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