Re: dbdebunk 'Quote of Week' comment
From: Marshall Spight <marshall.spight_at_gmail.com>
Date: 26 Aug 2005 09:34:30 -0700
Message-ID: <1125074070.799079.80320_at_z14g2000cwz.googlegroups.com>
> This means that there must be a one to one mapping between the generated key
> and some key with a meaning for the end user. Therefore that meaningless
> primary key is a pointer. But one of the goals of the relational model is to
> eliminate pointers from the data model.
Date: 26 Aug 2005 09:34:30 -0700
Message-ID: <1125074070.799079.80320_at_z14g2000cwz.googlegroups.com>
x wrote:
>
> This means that there must be a one to one mapping between the generated key
> and some key with a meaning for the end user. Therefore that meaningless
> primary key is a pointer. But one of the goals of the relational model is to
> eliminate pointers from the data model.
I'm not sure I share this point of view. I propose that every pointer is meaningless; every key is meaningful, whether system generated or not. The meaning is exactly that it is the identity of the row. A randomly-generated customer id still means something.
Another difference between keys and pointers is that keys are content-addressible, while pointers are location-addressible.
The differences between keys and pointers are small and sometimes subtle, but useful nonetheless.
Marshall Received on Fri Aug 26 2005 - 18:34:30 CEST