Multidimensional order preserving linear hashing with partial expansions

Abstract

We present a new multidimensional dynamic hashing scheme without directory intended for files which grow and shrink dynamically. For previous schemes, the retrieval performance either suffers from a superlinearly growing directory or from an uneven distribution of the records over the pages of a file even for uniform record distribution. Our scheme is a multidimensional order preserving extension of (one-dimensional) linear hashing with partial expansions and thus overcomes these disadvantages. For uniform distribution our scheme performs better than its competitors which is underligned by experimental runs with an implementation of our scheme. In the last section we give a brief outline of the quantile method which guarantees that our scheme performs for a non-uniform distribution practically as well as for a uniform distribution. In addition to its excellent performance, our scheme fulfills all the necessary requirements to be used in an engineering database system: it is dynamic, is suitable for secondary storage devices, supports point data and spatial data objects and supports spatial clustering (proximity queries).