Re: native xml processing vs what Postgres and Oracle offer

From: paul c <>
Date: Mon, 01 Dec 2008 22:50:18 GMT
Message-ID: <KSZYk.1597$yK5.634_at_edtnps82>

Brian Selzer wrote:
> "paul c" <> wrote in message
> news:fqSYk.1429$yK5.577_at_edtnps82...

>> Brian Selzer wrote:
>>> "paul c" <> wrote in message 
>>> news:nUeXk.560$si6.520_at_edtnps83...
>>>> rpost wrote:
>>>>> paul c wrote:
>>>>>> wrote:
>>>>> [...]
>>>>>>> Actually, usenet is often displayed as being hierarchical, for
>>>>>>> instance with so called "threaded" newsreaders, because within a list
>>>>>>> of discussions, replies to replies are often more comprehensible when
>>>>>>> you can follow the subthreads.
>>>>>>> ...
>>>>>> Nobody said there's anything wrong with hierarchical displays (or
>>>>>> hierarchical physical storage for that matter).
>>>>> [...]
>>>>>> As the general level of literacy continues to decline more and more of
>>>>>> those who fail to recognize the possibility of a logical model will 
>>>>>> have
>>>>>> to put up with that dwindling breed.
>>>>> You're evading the question.
>>>>> ...
>>>> What question would that be?  (The original question was to do with the 
>>>> best product to use to display hierarchical data.  The OP planned to 
>>>> invent his own forum, presumably not Usenet-based.  I pointed out that 
>>>> he was wrong to assume a forum is hierarchical.)
>>> Pardon me for sticking my nose in, Paul, but you are ignoring facts as 
>>> plain as day: The content of a forum is a directed graph without any 
>>> circuits--that is, a collection of trees--each message being a node and 
>>> each response being a directed edge.  How can you possibly argue that it 
>>> is not heirarchical?
>> I'm amazed that in this day and age there can be any dispute about 
>> something so simple.  As I said before, one may choose to display messages 
>> in a hierarchical way, but that is not at all the same thing as basing a 
>> server or reader on a hierarchical model.

> I didn't say anything about a heirarchical model. I'm arguing that the
> content of a forum--messages and responses to messages--is in essence
> heirarchical. This is not about how messages are displayed, it's about what
> they are: each message either starts a topic or is a reply to another
> message.
> ...

The OP clearly had XML in mind. While I don't think it's any kind of coherent data model (eg., structure that involves only syntax and operators that are catch-as-catch-can without the kind of foundation of the boolean ops and predicate logic) and while it's not obvious that the OP claimed any such thing, I feel quite justified in jumping on anybody who brings XML up as some kind of data design solution in a theory group.

On top of that, some people who know quite a lot of detail about the RM then piped up (including you, for shame) to persist in encouraging the Humpty-Dumpty kindergarten school of design that imagines appearance is everything. To quote the OP: "mapping between GUI and data is oh so easy with hierarchies, compared to relations". That makes it clear to me that he is confusing the logical model with presentation/display.

>> The essence of a hierarchy is position and record order.  Position ignores 
>> the Information Principle and the order is logically extraneous.

> The essence of a heirarchy is precedence. A heirarchy is a collection of
> individuals (objects) connected in such a way that each individual has at
> most one direct predecessor and that no individual can be a direct or
> indirect predecessor of itself. Records and the position of records are at
> best orthogonal.

That's fair enough. I should have said the essence of the hierarchical programming schemes (not models, which XML isn't - I think Codd was being kind to even suggest that it is reasonable to compare his model to a hierarchy, those being apples and oranges) is position and order.

(What the programming hackers seem to perpetually miss, is not so much the question of whether relational ideas are superior, but the idea of a formal logic to guide and gauge data designs. This is reminiscent of political arguments I read in the daily general press. The world would be no worse off if they would try to apply the same discipline to their creations. I for one don't think it inconceivable that something even better might result. But I refuse to compare apples to oranges outside of the kitchen.) Received on Mon Dec 01 2008 - 23:50:18 CET

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