I have an object where I add a dictionary type object to record some information and I create one of these items/piece of information. Sorting is not needed and before I had it implemented as a list of dictionaries however that caused some problems. Mainly the ZODB starting getting huge very fast since the entire data structure would get copied everytime it was made. I then created an OOBTree and that worked a lot better and I just used a timestamp as the unique index however it seems that I don't really need a type with an index like that however when I tried to use OOSet it had the same behavior as the list of dictionaries did. ie It got big very fast. Should OOSet grow very quickly with newer items added to it? What is the best way to add items to it if it should not? I used insert(object) Is there a drawback to using OOBTree to replace almost any use of a python dictionary for a complex object since it seems to allow an object to have its subobjects change without having the entire thing saved again? Thanks Designing and building web applications http://webme-eng.com