If you haven't actually looked at the code, you might want to avoid making such a overly-general statement. CDB is a very simple data structure (basically a two-stage hash table) serialized to disk in a format that makes lookup fast. You can check the link I posted above to see a simple explanation of the format, and this page to see examples for usage (from an API-compatible reimplementation):

http://www.corpit.ru/mjt/tinycdb.html

Since the core algorithm is so simple, creating a 64-bit version should be similarly easy, at least on a UNIX-like system (trying to run code designed by Dan Bernstein on a non-UNIX system would be...interesting).