Re: how to link different but related tables
From: Jerry Stuckle <jstucklex_at_attglobal.net>
Date: Tue, 15 Mar 2016 11:09:02 -0400
Message-ID: <nc98cc$gee$1_at_jstuckle.eternal-september.org>
>
> In such an extrem case, one might consider to use base
> tables that are denormalized and contain NULLs for the
> attributes that do not apply. Denormalization is usually an
> anti-pattern, but might be appropriate at times. But this
> might have its own performance issues.
>
> Another anti-pattern are »dynamical attributes«. I.e.,
>
> Product Property Value
>
> 1211 Weight 200 kg
> 1211 Height 10 m
> 1212 Size 200131 Bytes
>
> But in extreme cases patterns that usually are
> anti-patterns might have to be considered.
>
Date: Tue, 15 Mar 2016 11:09:02 -0400
Message-ID: <nc98cc$gee$1_at_jstuckle.eternal-september.org>
On 3/15/2016 10:27 AM, Stefan Ram wrote:
> ram_at_zedat.fu-berlin.de (Stefan Ram) writes:
>> Performance issues might arise.
>
> In such an extrem case, one might consider to use base
> tables that are denormalized and contain NULLs for the
> attributes that do not apply. Denormalization is usually an
> anti-pattern, but might be appropriate at times. But this
> might have its own performance issues.
>
> Another anti-pattern are »dynamical attributes«. I.e.,
>
> Product Property Value
>
> 1211 Weight 200 kg
> 1211 Height 10 m
> 1212 Size 200131 Bytes
>
> But in extreme cases patterns that usually are
> anti-patterns might have to be considered.
>
This is one way to do it - but it is very unfriendly. What if you want to sort by weight, for instance? Which is why it fails first normal form ("the domain of each attribute contains only atomic values").
-- ================== Remove the "x" from my email address Jerry Stuckle jstucklex_at_attglobal.net ==================Received on Tue Mar 15 2016 - 16:09:02 CET