[Info-ingres] Re: is there an equivavlent to auto_increment in ingres ?

At 2:30 AM -0700 7/20/05, --CELKO-- wrote:
>> A better example is FedEx/UPS/DHL. A package's "tracking number" is a definite surrogate key. No doubt about it. <<

No, no, no;  those are not surrogate keys.  Go back to my post and read
Dr. Codd's definition.  They are "intelligent keys" that can be put in
a bar code and used by machinery to track and to route a package.  They
have check digits, the destination, etc. in the created key.

In the book trade, we have the SAN (Standard Address Number) which was
used for shipping and controlled by a trusted outside source.
Bookdealers, publishers, etc. were not in the shipping, so this was
pretty handy.  FedEx/UPS/DHL et al **are** the shipping business, so
they have to be their own internal trusted source.


I'm not sure I agree.  I don't think FedEx/UPS/DHL considers the
"tracking number" as merely an intelligent key used by machinery.

Some experience with their systems tells me they are used as the
primary key for everything.

Remember the consumer experience with shipping is very simple.  99%
of us never have more than one item in transit at any one time.

But shippers work with multi-national companies that ship 100,000
items per day from 100 locations to 30,000 destinations at varying
urgencies, transports, and shipping specifications.

Thinking about it, I guess they aren't surrogate keys, as they are
exposed to the user and not sitting side by side with the logical
primary key.  I suspect they started as surrogate keys.

When the truly logical primary key is so hideously verbose an
complex as a shipped package's tracking identifier, the human mind (in my
opinion) reverts to something easier to represent it.  I don't think
anyone relates to package "12395757631923" by anything other than
that number.  I don't think people mentally substitute the dozen or
so unique fields that logically distinguish one shipped package
from another.

So I'm not sure if we agree or disagree.  But I really can't see how
we can live without abstract "keys" exposed to users in everyday
life.

Cheers,

--
Michael Leo               Java, J2EE, BEA WebLogic,
Caribou Lake LLC          Oracle, Open Source, Ingres,
mleo@xxxxxxxxxxxxxxx      Real Enterprise Applications
.

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