A starting point is http://www.zope.org/Members/anthony/sql_vs_ZODB
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 implementation problems I don't know how to solve at the moment. Can somebody elaborate on 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 choose 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 which 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.