NIST

spiral storage

(data structure)

Definition: A dynamic hashing table that grows a few slots at a time. It uses a hash function, h, with a range of [0,1). For a key, k, an intermediate value, x=⌈ S-h(k)⌉ +h(k), is computed to find the final slot, ⌊ dx⌋, where d>1 is called the growth factor. To increase the number of slots, increase S to S' and rehash any keys from ⌊ dS⌋ to ⌊ dS'⌋-1.

Generalization (I am a kind of ...)
dynamic hashing.

See also linear hashing.

Note: Choosing d=2 and S=log2N, the number of slots, every expansion retires one slot and creates two new slots. Since slots in use go from ⌊ dS⌋ to ⌊ dS+1⌋-1, they are usually remapped to physical storage.

Author: PEB

More information

G. N. N. Martin, Spiral storage: Incrementally augmentable hash addressed storage, Theory of Computation Rep. 27, Univ. of Warwick, England, 1979.

Per-Åke Larson, Dynamic Hash Tables, CACM 31(4):446-457, April 1988.


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Entry modified 25 July 2006.
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Cite this as:
Paul E. Black, "spiral storage", in Dictionary of Algorithms and Data Structures [online], Vreda Pieterse and Paul E. Black, eds. 25 July 2006. (accessed TODAY) Available from: https://www.nist.gov/dads/HTML/spiralStorage.html