dbh -- Disk based hash library
http://www.xfce.org/
Disk based hashes is a method to create multidimensional binary trees
on disk. This library permits the extension of database concept to
a plethora of electronic data, such as graphic information. With the
multidimensional binary tree it is possible to mathematically prove that
access time to any particular record is minimized (using the concept of
critical points from calculus), which provides the means to construct
optimized databases for particular applications.