Le jeu 26/06/2003 à 23:43, Dieter Maurer a écrit :
A relational database essentially supports a single data type: a two dimensional table.
hmmmmph ! you are not serious, are you ? I don't know of any RDBMS which doesn't support primitive types (int, float, bool, char, string).
The ZODB supports an openly extensible set of data types.
What is more extensible that the combination of primitives types + relations + inclusion constraints ? Lacks encapsulation, inheritance, as in OO ? Hopefully no serious DB backend provides true OO semantics since those don't exist (OO semantics are really defined at the level of the language itself). Relational algebra on the contrary has solid grounds in set and predicate theory. You can map any "OO model" into the relational model. Not the other way around.
This might be considered "less straightforward to understand". It definitely is not a flaw.
The flaw lies in this fact : ODBMS are really hierarchical DBMSes, like the ones of the 60's and 70's that the relational model was supposed to help throw out of the window. That's not to say ZOBD isn't neat and usefull, but please. I just hate when some knowledgeable person spreads FUD on those topics. Aurelien.