[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message]

Re: 2 questions about Relax NG: ID/IDREF datatype and w hitesp

• From: "Peter Hunsberger" <peter.hunsberger@g...>
• To: "Len Bullard" <len.bullard@u...>
• Date: Thu, 15 Nov 2007 16:33:28 -0600

On Nov 15, 2007 4:09 PM, Len Bullard <len.bullard@u...> wrote:
> The interesting questions
>
> 1.  Are such ratios common?
>

Sorta doubt it. If you've got well defined business rules people tend
to hard code everything and assume the rationale behind the now
embedded / partially hidden metadata is well understood...

> 2.  Why do some designs or domains have such high proportions of metadata
> entities to data entities?
>

If you look at where people are using EAV type databases you'll see
Research and Clinical trials come up; we're both, so I guess that
partially explains it for us: basically, if you're going to do
dynamically generated GUI's  you're going to need configuration tools
that both create and consume metadata in large quantities.

The other existing area that might see large ratios is where RAD tools
are prevalent.  Which makes me think that with a tend towards model
driven development this might start to become more common in other
domains as well.


> len
>
>
> From: Peter Hunsberger [mailto:peter.hunsberger@g...]
>
> I had sent this reply to Len off list, but it's sort of an interesting
> debate so here it is again:
>
> If you're collecting research data then, off hand, I'd say about 90%+:
>  we're using a strongly typed version of a EAV model, only 5 tables
> out of the 40 or so involved in the model actually collect the actual
> data.
>
> I had figured Len would come in high but not that high, instead he
> agreed.  I actually think we can drop that ratio by recursively using
> the data tables to store the metadata; sort of an uber schema. There
> seems to be a belief in some circles that such a design result in a
> lot  of extra joins, but in my experience if it's done right that's
> not particularly true...
>


-- 
Peter Hunsberger

• References:
  • RE: 2 questions about Relax NG: ID/IDREF datatype and whitespace facet
    • From: Len Bullard <len.bullard@u...>