Re: A question for Mr. Celko
Date: Sat, 17 Jul 2004 23:23:18 GMT
Message-ID: <pan.2004.07.17.23.23.54.257337_at_REMOVETHIS.pandora.be>
On Sat, 17 Jul 2004 15:37:00 +0000, Marshall Spight wrote:
> "Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message
> news:pan.2004.07.17.10.58.17.83649_at_REMOVETHIS.pandora.be...
>>
>> One criticism I heard is that to simulate the PACK and UNPACK operators
>> you have to use operators that violate 1NF as it is usually understood.
>> But note that the exact definition of 1NF is not as well-understood as
>> one might suppose. Chris Date, for example, apparently has decided to
>> trivialize the notion.
>
> Is there any reason it shouldn't be trivialized? 1NF doesn't seem to do
> anything but get in the way of things like relation-valued or
> list-valued attributes.
Good question. I would argue that it keeps things simple. I don't see a problem with that at the *user* level but at the *logical* level you want to make things as simple as possible for the query optimizer. Much that same as the usual arguments for not having bags and null values. And, of course, you also might want to have a representation that is not biased towards one of the views at the user level. So it is not so evident to me that what is ideal at the user level is also ideal at the logical level.
- Jan Hidders