New Bounds for Perfect Hashing via Information Theory
نویسندگان
چکیده
منابع مشابه
Dynamic Perfect Hashing: Upper and Lower Bounds
The dynamic dictionary problem is considered: provide an algorithm for storing a dynamic set, allowing the operations insert, delete, and lookup. A dynamic perfect hashing strategy is given: a randomized algorithm for the dynamic dictionary problem that takes O(1) worst-case time for lookups and O(1) amortized expected time for insertions and deletions; it uses space proportional to the size of...
متن کاملUniversal Hashing and Perfect Hashing
Each of the key values x comes from a universe U , i.e. x ∈ U . In this document, we assume U = {1, 2, . . . N}. Observe that the set S is a dynamic set. Each of the Insert and Delete operations may modify the set. Hence the size of the set S changes with each operation. We bound the maximum size of the set to n (n << N). What are the data structures that can be used to store the set S? One opt...
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Consistent Hashing functions are widely used for load balancing across a variety of applications. However, the original presentation and typical implementations of Consistent Hashing rely on randomised allocation of hash codes to keys which results in a flawed and approximately-uniform allocation of keys to hash codes. We analyse the desired properties and present an algorithm that perfectly ac...
متن کاملTheory and Practise of Monotone Minimal Perfect Hashing
Minimal perfect hash functions have been shown to be useful to compress data in several data management tasks. In particular, order-preservingminimal perfect hash functions [12] have been used to retrieve the position of a key in a given list of keys: however, the ability to preserve any given order leads to an unavoidable (n log n) lower bound on the number of bits required to store the funct...
متن کاملPractical Perfect Hashing
A practical method is presented that permits retrieval from a table in constant time. The method is suitable for large tables and consumes, in practice, O(n) space for n table elements. In addition, the table and the hashing function can be constructed in O(n) expected time. Variations of the method that offer different compromises between storage usage and update time are presented.
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ژورنال
عنوان ژورنال: European Journal of Combinatorics
سال: 1988
ISSN: 0195-6698
DOI: 10.1016/s0195-6698(88)80048-9