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Message Posted: Sat, 20 Apr 2002 @ 18:11:20 GMT

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Subj:   Re: Nulls in a composite Primary Key deployed as a Primary Index
From:   John HR Schuster

John Wight makes a good point PI <> PK. Some other RDBMS don't handle that concept well or at all. Those coming from something other than Teradata might have difficulty with it.

NULL does actually means something or rather the "lack of something". As most know NULL is not zero or blanks but the "lack of something". In the original case where the customer doesn't have all the parts of data for a PI at the time of loading that is a "Lack of something". By putting 9999's in a field that indicates a something unless you create a new rule that states 9999's is a code for "lack of something". I don't like to have special codes in my DB's that I hjave to explain, document and handle with ever DB or BI tool is use, I know the 3NF folks will cringe.

Can anyone explain how NULL's affect the hashing power of Teradata? That might be more the concern.

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