Hi! We are currently developing a groupware system with Zope. As usual, the options for the storage back-end are using a SQL DB (postgres, ...) or ZODB. I know that this question has been asked a thousand times. But I'll repeat it for our specific situation: SQL or ZODB+ZCatalog, which one is better? We have thousands, maybe millions of objects (mainly mail messages, notes, appointments). There should be very flexible views on the data, e.g. a message or document can either be viewed on the owner's personal workspace or on the project portal the document was posted to. The problems with SQL: - much more complex setup - problems with using ZEO - BLOBs (large binary objects like image files) don't work well on most databases The problems with ZODB/ZCatalog: - ZCatalog is not tested for extremly large numbers of objects. We fear that the index tables will become much too big - Some advanced queries are very hard to implement using ZCatalog Any comments? Joachim.