Maybe you need an ORDB (Object-Relational DB) like postgresql.  PGSQL
supports Inheritance:


-----Original Message-----
From: Luciano Ramalho [mailto:[EMAIL PROTECTED]]
Sent: Monday, January 22, 2001 6:12 AM
To: Tom Deprez
Cc: Rik Hoekstra; [EMAIL PROTECTED]
Subject: Re: [Zope] Object DB versus Relational DB

ZODB with Data.fs is optimized to fetch data. Inserts or updates have a
lot of overhead. It's the price we pay for the excellent versioning
features. Therefore, when the are many  we have been avoinding ZODB even
when the problem domain calls for an OODB

We have implemented a highly hierarchical database for a Yahoo-like
directory using a recipe found in the book SQL for Smarties, by Joe
Celko, ISBN 1-55860-323-9 (see Chapter 26 - Trees).

Celko's solutions allow for a hierarchy with unlimited levels and,
amazingly, it does not require sub-selects or any other construct
unsupported by MySQL.

The rest of the book is filled with solutions to problems that test the
limits of the relational database model.

Best regards,

Luciano Ramalho

Tom Deprez wrote:
> > A starting point is
> Reading this text is exactly the problem I'm having. Unfortunately, it
> doesn't give much examples.
> I hope somebody can give me some answers on my question :
> The problem I'm facing is the following. I've got a lot parent-child
> relationships -> OODB
> But, I also need to perform some queries on these records and link some to
> each other -> more RDB.
> I'm not sure which way to follow. A hybrid solution isn't the best one, I
> think, because then you do twice the same work. ie. You've to create the
> parent-child relationship in the OODB (the site structure) and in the RDB
> (to perform correct queries).
> The RDB solution is possible, but since I need lots of parent-child
> relationships not the best one.
> The OODB is probably the best. However, this implies several
> problems I don't know how to solve at the moment. Can somebody elaborate
> the following questions? Thanks in advance.
> Assume the following :
> Group1
>    SubGroup1
>       SubGroupA
>           Problem1
>               Examination1
>                         Equipment1
>                               Paremeters
>                         Equipment2
>                               Parameters
>               Examination2
> ....
> Campus1
>    Room1
>      Equipment1
>      Equipment2
>    Room2
> ....
> Now,  if a person is creating a new equipment in Examination2. How can I
> show it all the avalailable equipments in Campus1? So this person can
> from it and create it in the examination2 folder? In an OODB environment?
> If a person is browsing in Room1 and wants to get all the examinations
> will be performed on Equipment1. How do I create such a query in OODB? (Or
> even further, the person wants to see all the examinations done on
> equipment1, but only with Group=Group1 and SubGroup=SubGroup1
> How can this be done in Zope?
> Thanks in advance,
> Tom.
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