[Zope] Big folders

I've been studying SQL this week because I've been thinking that I'll probably have to use a RDBMS to develop my site. Ideally and philosophically I like ZODB. Mountable ZODBs give me much of what I need with the possible exception of a big folder problems. My databases will have millions of objects in what would/will be single table/folders. From what I understand ZODB doesn't currently do big folders well. So I guess my question is, should I continue with the SQL and the RDBMS or is there a solution that I don't know about or understand with ZODB? My apologies if this covered somewhere. Jimmie Houchin