Discussion of "dbm" data base system

[Spencer W. Thomas]

Gosling (of emacs fame) did some work on the dbm package (producing
something called ndbm).  His changes include the ability to have
multiple data bases open at once.  I don't know about the internals, but
ndbm files have 3 files, a ".dat", ".dir", and ".pag" file.  I think he
tried to solve the page-splitting problem by moving the actual data into
a third file, which is pointed to from the second one (the one which, in
dbm, would contain the data), which now contains only keys and pointers,
making it much more likely that all records hashing to one page will fit
into the page.  On the minus side, there is no reclamation of space in
the data file (this is also a plus, if you screw up and want to
recover), so you have to dump and reload the database every now and then.

Can anybody out there enlarge on this?

=Spencer