Re: Proposal: 6NF

"Cimode" <cimode_at_hotmail.com> wrote in message news:1159797534.237592.159150_at_e3g2000cwe.googlegroups.com...
>
> Brian Selzer wrote:
>> "Roy Hann" <specially_at_processed.almost.meat> wrote in message
>> news:P-Sdnd58Trp7GYLYnZ2dnUVZ8tGdnZ2d_at_pipex.net...
>> > "David Portas" <REMOVE_BEFORE_REPLYING_dportas_at_acm.org> wrote in
>> > message
>> > news:1159692483.421785.264660_at_c28g2000cwb.googlegroups.com...
>> >> Brian Selzer wrote:
>> >>>
>> >>> The argument JOG made focused only on recording information, not
>> >>> retrieving
>> >>> it. Why would anyone abandon a sound mechanism that can
>> >>> significantly
>> >>> reduce the computing capacity required to answer a query?
>> >>
>> >> Because your argument is merely an assumption based on what some
>> >> systems of today are capable of.
>> >
>> > It's worse. His entire position is based on not knowing even what some
>> > of
>> > today's products are already capable of. For example, he seems unaware
>> > of
>> > the role of the optimizer.
>> >
>>
>> I understand fully the role of the optimizer. That's one of my points.
>> If
>> you arbitrarily split a table with a nullable column, then you're robbing
>> the optimizer of possible execution plans. It may make sense to split a
>> table, for example, removing non-key columns that are seldom used in
>> queries
>> into another table in order to boost the performance of all other
>> queries.
>> The point I'm trying to make is that the decision should not be
>> arbitrary.
> Consequences of NULL uses goes far above he simple problem of
> execution. It hinders performance at all levels (response time,
> concurrency) and introduces a very strong part of subjectivity in
> interpretation of data presented to users.
>

I don't agree. Judicious use of NULL can improve performance, response time, and concurrency. In addition, when used correctly, no subjectivity is introduced. For every database schema with NULLable attributes, there is always an equivalent schema without. Any subjectivity would therefore be independent of the database schema. On the other hand, arbitrary or incorrect use of NULL can cause all of the problems you describe.

>> > Roy.
>> >
>
Received on Mon Oct 02 2006 - 17:26:01 CEST