Re: Conceptual, Logical, and Physical views of data

From: Marshall Spight <>
Date: 10 Sep 2005 23:05:51 -0700
Message-ID: <>

dawn wrote:
> > ...It has to do with
> > the nature of the *operator* you apply to get the results. With a Url,
> > let's call that operator GET. Can you do anything with GET besides
> > give it a Url and get back HTML? No; so it's a pointer; it exists
> > only in the context of a dereference operator. Without GET, the Url
> > is useless; it doesn't tell you anything.
> I suspect I'm just not thinking clearly, because I don't see the
> difference between that and a social security number for a person. The
> SSN tells me nothing without the operations to retrieve the person who
> has been assigned that SSN.

Consider: if you know *only* a person's SSN, do you know anything about the person? Yes! You know their SSN. If you picked that person's records up out of the system they're currently in and moved them to another completely different server, maybe even change from SQL to, uh, flat files, would the SSN change? No! It's the same, regardless of the medium.

Let's say that the HTML document in question contains the exact same information about the person as the relational records. Now let's say you know *only* the URL of that document. Do you know anything about the person? Not a bit. Let's say you pick that HTML doc up and move it to a different server, would the URL change? You bet it would.

See the difference?

> > Now, if you could supply GET with some attributes of the document
> > itself, that would be different. Let's say you could say:
> >
> > GET title like "foo"
> >
> > and get back all the documents on the web that had "foo" in the title.
> Like google, but with attribute names instead of all data being
> identified in the value of the document, such as could be the case if
> the html were xhtml and a query language were employed?

> > Anyway, you're totally going down the wrong path with your focus
> > on the web-as-database, anyway.
> I didn't call it a dbms. Do you want to toss out your def of
> "database" so that the web doesn't conform, or of "attribute" so that a
> document cannot be the value of one? [she asks, goading him]

I like the classic "a database is a collection of facts" and the classic "dbms handles structure, integrity, and manipulation." A document can certainly be a fact or a collection of facts. But I note that HTML and HTTP have little in the way of facilities for formal structure (it's pretty much semantic-free markup) and exactly nothing in the way of integrity and manipulation.

Marshall Received on Sun Sep 11 2005 - 08:05:51 CEST

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