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

In message <3fqdnUHV_-Qf__jeRVnyjQ_at_pipex.net>, Roy Hann <specially_at_processed.almost.meat> writes
>"Bernard Peek" <bap_at_shrdlu.com> wrote in message
>news:9Dc+bybsWUZDFw5n_at_shrdlu.com...
>
>> That's one reason why people keep trying to use it. The second one,
>> unfortunately, is that sometimes it's the only alternative. Sometimes
>> you just don't know the whole data structure at design-time.
>
>One day, ours will be a real profession, and we'll be allowed to say "sorry,
>you can't do that" without getting fired. In fact we'll have a legal duty
>to say it, just like engineers and accountants and proper professionals.

But that's not the problem. The problem is that it is possible to build a database using the EAV system, but it will require constant maintenance and skilled users to keep it working. That's why it has to be a fall back option, only used when there are no other alternatives.

I wonder whether there's a role for EAV systems in prototyping systems using agile development? An EAV database could be used to collect metadata during the early development stages, and that metadata could then be used to build the final database system, replacing the temporary EAV model.

-- 
Bernard Peek
London, UK. DBA, Manager, Trainer & Author.