persistent dictionary with non-string keys

[San71]

I'm writing an application which creates a rather large dictionary (>
500 MB) from MySQL data. It is a dictionary which uses integers,
tuples, and datetime instances as keys. I've tried shelve (str() en
eval() for the integer and tuples), but of course, that doesn't solve
it, because I also need to keep the datetime instances intact as a
key. Is there a way to make this dictionary persistent?