Algorithm for Dynamic Partitioning and Reallocation of Fragments in a Distributed Database

Given the fact that the volume and the diversity of data grow considerably year by year, the problem of efficient data management rise because the data must be available at any time and must be accurate. In this paper is proposed a heuristic algorithm for fragmentation and reallocation of new fragments to other sites in an unbalanced system in order to obtain an optimal dynamic distribution of data fragments with the smallest possible cost. The dynamic characteristic of the model consist in the fact that the change of access models (read, write) must lead to the re-fragmentation and reallocation of fragments and creation or deletion of fragments replicas (the fragments replicas can change their rights) depending on the users data access histograms. These decisions are taken by algorithms utilizing cost function which estimate the difference in future communication costs between the change of a given replica and keeping that replica on the actual condition. The proposed model can be applied also in parallel databases because every site take decisions about their own fragments and the decisions are taken without any site synchronization.