Re: Modelling objects with variable number of properties in an RDBMS

From: VC <boston103_at_hotmail.com>
Date: Wed, 2 Nov 2005 06:00:46 -0500
Message-ID: <P6KdnREFdtrKAfXeRVn-jQ@comcast.com>

"Jonathan Leffler" <jleffler_at_earthlink.net> wrote in message news:YHY9f.4683$Rl1.3852_at_newsread1.news.pas.earthlink.net...
> VC wrote:

>> "Roy Hann" <specially_at_processed.almost.meat> wrote in message 
>> news:9v-dnYE-SanY6PreRVnygg_at_pipex.net...
>>
>>>"vc" <boston103_at_hotmail.com> wrote in message
>>>news:1130765800.098046.93870_at_f14g2000cwb.googlegroups.com...
>>>
>>>>Roy Hann wrote:
>>>>....
>>>>
>>>>>Actually no, let's not.  What you have re-invented here is the tired 
>>>>>old
>>>>>entity-attribute-value (EAV) design (much beloved of medical research
>>>
>>>wonks
>>>
>>>>>for some reason).
>>>>
>>>>Often they do that (EAV) not because they do not know any better but in
>>>>order to overcome a specific database physical limitations. Their
>>>>entities very often contain thousands of attributes (molecular
>>>>biology/pharmaceutical research/drug discovery) [snip].
>>>
>>>Always check the bath water for babies...
>>
>>
>> I beg your pardon ?
>
>

> There's an old saying "Don't throw the baby out with the bath water".
> In this context, it means (roughly) make sure you don't lose the benefits
> of the relational model by thowing away all the rules that help

I know that, but what recipe does Roy suggest for, let's say, MS SQL Server that does not have either UDTs or other means to implement an entity with a higher than the table limit number of attributes, beyond offering a cute saying ?

> make it work.

>
>


> -- 

> Jonathan Leffler                   #include <disclaimer.h>

> Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com
> Guardian of DBD::Informix v2005.02 -- http://dbi.perl.org/
Received on Wed Nov 02 2005 - 05:00:46 CST