primary clustering


Definition: The tendency for some collision resolution schemes to create long runs of filled slots near the hash function position of keys.

See also secondary clustering, clustering free, hash table, open addressing, clustering, linear probing, quadratic probing, double hashing, uniform hashing.

Note: Primary clustering increases average search time. Linear probing is especially susceptible to primary clustering. Clustering may be minimized with double hashing.

Author: PEB

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Entry modified 18 July 2005.
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Cite this as:
Paul E. Black, "primary clustering", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed. 18 July 2005. (accessed TODAY) Available from: