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Judy libraries

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Judy Library

Judy is a C library that provides a state-of-the-art core technology that implements a sparse dynamic array. Judy arrays are declared simply with a null pointer. A Judy array consumes memory only when it is populated, yet can grow to take advantage of all available memory if desired.

  • Judy's key benefits are scalability, high performance, and memory efficiency.
  • A Judy array is extensible and can scale up to a very large number of elements, bounded only by machine memory.
  • Since Judy is designed as an unbounded array, the size of a Judy array is not pre-allocated but grows and shrinks dynamically with the array population.
  • Judy combines scalability with ease of use. The Judy API is accessed with simple insert, retrieve, and delete calls that do not require extensive programming.
  • No tuning or configuring are required (in fact are not even possible).
  • Sort, search, count, and sequential access capabilities are built into Judy's design.
  • Judy can be used whenever a developer needs dynamically sized arrays, associative arrays or a simple-to-use interface that requires no rework for expansion or contraction.
  • Judy can replace many common data structures, such as arrays, sparse arrays, hash tables, B-trees, binary trees, linear lists, skiplists, other sort and search algorithms, and counting functions.
  • For more information on Judy, please visit the Judy webpage at
Additional product information
Product #: Judy
Version: -
Software specification: HP-UX11.23 IA/PA
HP-UX11.31 IA/PA
Installation Support