[Zope] undo machinery mysteries

[Jeff Sacksteder]

Is there a way to protect objects from removal due to ZODB compaction and
still maintain undo and revision history? You could consider the the
opposite of a 'Temporary Folder'. For certain documents, I would like to
keep ALL previous versions in the object store forever- superpersistant, if
you will. 

The best way that I can think to approach this is to keep my superpersistant
objects in a second ZODB and mount it in a folder in my primary ZODB. I
could then compact my primary without losing old revisions of my files.

Is there a better way to approach this?