Erik..

I understand the point you are attempting to make. Of course you knew that I would be prepared...< bg >...

Lets review what the 2nd NF is. A table is considered to be in the 2nd NF when redundant data is eliminated.

Question, in the scenario I described, is their likely to be redundant data? The answer is yes.

Therefore, I have elected not to normalize the lineitems with respect to item description for the purposes of historical reporting. It can easily be argued that if normalizing a table is going in one direction, what I have described is going in the other direction; the opposite of normalization.

I think a distinction has to be made between what a data entity is and the piece of information a data entity contains. At inception, when the lineitem was created, the description in the lineitems table and the descrition in the items table were the same. That is to say, the information contained was the same.

On a logical basis, one could make the argument that regardless of where the item description is carried, it is the same "thing". On a physiscal basis, they are different.

The real difference between the two - the lapse in time.

Your analysis below deals with the issue in a phyiscal sense. Normalization OTOH, is one in the realm of design - in dealing with a logical model. Ultimately, the results of normalization are manifested in a physical database.

Here is a mind-bender...does one normalize a database? Or, does one normalize the model - which ends up being manifested in the physical database? Or, are they the same? Or, does it matter as it is an argument over semantics?

FWIW, I think it is the latter...

As you could tell, I have not given this any serious thought at all..< bg >..

In the end, de-normalization as a term of art works just fine in this scenario.

However, if you are so inclined, what term of art would you coin for this scenario?

< JVP >






>Not to nit-pick, but this isn't really denormalization. If the item description for a lineitem needs to be recorded at the time of the invoice, and that description can later change independently of the invoice description, the current description and the historical description are two distinctly different pieces of information, and are not duplicated.