Alternating hashing for expansible files

Abstract

Proposes a generalized approach for designing a class of dynamic hashing schemes which require no index and have the growth of a file at a rate of (n+1)/n per full expansion, where n is the number of pages of the file, as compared to a rate of 2 in linear hashing. Based on this generalized approach, we derive a new dynamic hashing scheme called alternating hashing, in which, when a split occurs in page k, the data records in page k are redistributed to page k and page (k+1), or to page k and page (k-1), according to whether the value of level d is even or odd, respectively (d is defined as the number of full expansions that have happened so far). From our performance analysis, given a fixed load control, the proposed scheme can achieve nearly 97% storage utilization, as compared to 78% by using linear hashing.