You cannot easily tie a multilevel data structure (such as a hash of
hashes) to a dbm file. The first problem is that all but GDBM and
Berkeley DB have size limitations, but beyond that, you also have problems
-with how references are to be represented on disk. One experimental
+with how references are to be represented on disk. One
module that does attempt to address this need is DBM::Deep. Check your
nearest CPAN site as described in L<perlmodlib> for source code. Note
that despite its name, DBM::Deep does not use dbm. Another earlier attempt