Re: Generic Modeling

> Writing object database is easy,
An oodb should be more difficult since it is trying to represent and manipulate data in a more generic manner than in rdbs. For example in XDb, one can create 10 instances of 10 classes and arrange the resulting 100 objects in any imaginable hierarchy/arrangement (by simply cutting and pasting). An rdb is not as flexible.

> the only thing you need to master is recursion.
Does this bother you?

> No query parser,
When the above 100 objects can be arranged as randomly as in an oodb (or generic table design), traditional sql does not apply very well since it relies on rigid structuring of the data. Object based "sql" does exist but it is not a powerful as traditional sql (yet).

www.xdb1.com/Basics/Query.asp
www.xdb1.com/HowTo/CreateQuerySimple.asp
www.xdb1.com/HowTo/CreateQuery.asp

> no optimization

An oodb can be 10 to a 100 times fasters, especially when dealing with complex/variable data. Would you like to benchmark a specific example? Last time I couldn't get you to engage, you were very recursive.

> no concurrency.

You are correct. Currently none in XDb. Can't say for others.

> After serializing the whole memory to disc
> you just claim that you have (yet another) object database!
This must be very troubling since the concept of representing data as objects is unimagineable.

> Therefore, when you want to search for all broken(?) standard components
> you write:
>
> for( Country a = countries.first(); a!=null; a.next() ) {
> State[] states =a.states;
> for( State s = states.first(); s!=null; s.next() ) {
> City[] cities = s.cities;
> // 10 more levels to get to standard equipment
> }
> }
> ..

If the data fits "neatly" into rectangle tables and the relationships are rigid, then the traditional use of an rdb is best. Generic modeling or an oodb begins to show advantage as data complexity and variabililty increases. The above rigid loops would work well on data that have a rigid structure.
But if the equipment are scattered at various levels of the hierarchy and some of the levels are missing and the situation is different for each manufacturer the above rigid loops don't provide a generic solution. With a generic table design or an oodb approach, it is more often possible to write generic solutions.

If you can implement a generic deep instantiate as in XDb using an rdb, I would like to see it. (www.xdb1.com/Basics/ClassComplex.asp)

If you can implement a generic deep copy as in XDb using an rdb, I would like to see it. (www.xdb1.com/HowTo/CopyPasteObj.asp)

If you can implement a generic property rollup as in XDb using an rdb, I would like to see it. (www.xdb1.com/UI/Rollup.asp)

The traditional use of rdbs is the best solution for most problems, but if you try implement the above you may begin to see the need for generic modelling/oodb approach. Received on Thu Jan 03 2002 - 03:52:08 CET