Programming with Judy

Where Did Judy Come From?
Appendix A 59
A Where Did Judy Come From?
The technological innovations that eventually became the Judy code
were designed, implemented, and tested through more than a decade of
research and development at Hewlett-Packard. The time line below
shows the evolution of the Judy technology in HP internal products and
code releases to the HP programming community.
1981 Some of the basic concepts of the Judy technology
evolved from the RTE-6 Virtual Memory project
(firmware/software implementation of large data
indexing).
1991 Developing technology used in an internal performance
profiling tool project (saving profiles in digital trees).
1994 The Judy array structure discovered (digital trees used
instead of arrays for better performance).
1997 Judy re-engineered to handle random keys efficiently.
Digital trees did not work well for random keys.
1997 HP funds Judy for internal development (developed
efficient methods for storing random keys in digital
trees).
1999 Judy used in an internal HP application that required
the development of counting digital trees.
2000 HP staffs Judy as a project. In March 2000, a fully
functional, untuned concept version of Judy is available
internally.
2001 Judy Version 4.0, also known as Judy IV, available for
HP-UX 11i during March 2001.
Judy was invented at HP’s UNIX Software Enablement Laboratory at
Fort Collins Colorado. Hewlett-Packard has patents pending on the Judy
Technology.