Re: Little design mistakes that can be easily avoided (2): Listenning to CELKO (and CELKO alikes)

"Brian Selzer" <brian_at_selzer-software.com> wrote:

>
>"Matthias Klaey" <mpky_at_hotmail.com> wrote in message
>news:5f2k53pq5srphk68s1op58udei9h60stuo_at_4ax.com...
>> "Brian Selzer" <brian_at_selzer-software.com> wrote:
>>
>>>
>>>"Matthias Klaey" <mpky_at_hotmail.com> wrote in message
>>>news:bipi53pjf51gluul6b3b8uv86kbq7hanse_at_4ax.com...
>>>> Cimode <cimode_at_hotmail.com> wrote:
>>>>
>>>>>
>>>>>Matthias Klaey a écrit :
>>>>>> Cimode <cimode_at_hotmail.com> wrote:
>>>>>>
>>>>>> >On 26 mai, 18:18, Matthias Klaey <m..._at_hotmail.com> wrote:
>>>>>> >> Cimode <cim..._at_hotmail.com> wrote:
>>>>>> >> >Hi,
>>>>
>>>> [...]
>>>>
[...]

>>>>
>>>
>>>If you've studied it, they you know that Celko's failed to mention the
>>>last
>>>paragraph of section 4, which is in direct contradiction to his rant.
>>>I've
>>>pointed this and other things out to him before, but he still dumps the
>>>same
>>>flawed argument on people all the time. In other words, he *knowingly*
>>>mischaracterizes Codd's position to advance his own agenda. (He wants
>>>people to buy his books!)
>>
[...]

>> Or this one? Paper 2, Section 4 last paragraph
>>
>> "They will have to remember, however, that it is now the surrogate
>> that is the primary key and provides truly permanent identification
>> of each entity. The capability of making equi-joins on surrogates
>> implies that users see the headings of such columns but not the
>> specific values in those columns."
>>
>> And how, specifically, does any of these paragraphs contradict Celkos
>> "rant" (sic!)? Does it contradict the whole of it, or just part of it,
>> and if the latter is the case, which part?
>>
>
>This is the one. It directly contradicts the following paragraph in Celko's
>["rant" is a bit more polite than "spew" It certainly doesn't rise to the
>level of an argument. The fallacies and deliberate attempt to mislead place
>it more in the category of propaganda than anything else.]:
>
><<
>This means that a surrogate ought to act like an index; created by the
>user, managed by the system and NEVER seen by a user. That means
>never used in queries, DRI or anything else that a user does.

>
>Which sums up his entire argument against surrogates. He then uses the term
>"authority" as if in the article Codd was arguing against surrogates, when
>the section he quoted (or deliberately misquoted) is a clear argument in
>favor of surrogates! Now, while I'm not sure I agree with Codd when it
>comes to hiding surrogate key values, I certainly wouldn't twist his words
>completely around in order to support my own agenda!

I don't think that Celko argues *against* surrogates, in sharp contrast to "exposed physical locators". He clearly makes the distinction between the two types.

The only issue I see is about the visibility of surrogate key *headings* in equi-joins. The values have no meaning whatsoever to the user, as s/he cannot use them in Inserts, Updates, or Deletes.

I do not understand why it should be neccessary to display the headings of the surrogate keys in an equi-join. If I know that relations R and S have surrogate (primary) keys, I should be able to write a view

  equi-join(R, S)

without even having to know the names of the primary keys.

Greetings
Matthias Kläy

-- 
www.kcc.ch