Re: generic modelling of data models; enforcing constraints dynamically...

Have you considered contrib/hstore to build flexible database scheme ?

Oleg
On Sun, 27 Sep 2009, InterRob wrote:

> Dear David, dear Peter, dear all,
> Peter, I was happy reading your reply right after I opened and read Davids.
> I do think I am on the right track; it is not a matter of building the
> one-and-only right schema, not in this case. Archaeology has the same twist
> as has ethnography, antropology and alike: they work with (what I would
> call) "narratives" (in fact, in the case of archaeology this seems to me to
> be an archaeologists monologue...). They try to support their findings with
> statistics and other means of quatification -- as does this modern,
> rationalist world require them to do, to be taken seriously as science... I
> seek to implement all this in a hybrid form; a fusion between the relational
> and EAV concept.
>
> Peter, may I invite you to privately share some more details on the system
> you are using and the design of it? Did you implement it using PostgreSQL?
> Looking forward to your reply.
> (And with respect to your previous message: whom are you actually referring
> to by the acronym "OPs"?)
>
> Cheerz,
>
>
> Rob
>
> 2009/9/27 Peter Hunsberger <peter(dot)hunsberger(at)gmail(dot)com>
>
>> On Sun, Sep 27, 2009 at 2:22 PM, David Fetter <david(at)fetter(dot)org> wrote:
>>> On Sun, Sep 27, 2009 at 08:26:27PM +0200, InterRob wrote:
>>>> Dear David, dear all,
>>>> I very well understand what you are saying...
>>>
>>> Clearly you do not. What you are proposing has been tried many, many
>>> times before, and universally fails.
>>
>> I've been refraining from jumping on this due to time constraints, but
>> this statement is silly. We have a system that does almost exactly
>> what the OP wants although the implementation is slightly different:
>> we use an EAV like model with strong typing and build set / subset
>> forests to maintain arbitrary hierarchies of relationships. Our
>> reasons for doing this are similar to the OPs; it's for research (in
>> our case medical research). We maintain over 200,000 pieces of end
>> user generated metadata, describing what would be in a conventional
>> relational model over 20,000 columns and some 1,000s of tables but the
>> actual physical model is some 40 tables. Yes, the flip side is, such
>> a system won't support more than 1,000,000s of transactions per day,
>> but that's not why you build them.
>>
>>>
>>> That your people are failing to get together and agree to a data model
>>> is not a reason for you to prop up their failure with a technological
>>> "fix" that you know from the outset can't be made to work.
>>>
>>
>> Spoken like someone who has always had the luxury of working in areas
>> with well defined problem domains... I can't tell you the number of
>> people that told us exactly the same thing when we started on it.
>> That was 8 years ago. Not only can such systems be built, they can be
>> made to scale reasonably well. You do need to understand what you are
>> doing and why: the costs can be high, but when it comes to research,
>> the benefits can far outweigh the costs.
>>
>> --
>> Peter Hunsberger
>>
>>
>

Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg(at)sai(dot)msu(dot)su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83