But beware of MLDBM when attempting to store things that exceed the DBM's limitation, like 2K for SDBM. Can really ruin a day. Also, MLDBM wants
you to always change the top level hash to a completely new value. If you replace
something lower, you'll never see it in the data structure.
Because of these limitations, I prefer using Storable to throw the entire
thing into a file on my demand, rather than try to manage the top level piecemeal.