A heuristic approach to re-allocate data fragments in DDBSs

Fragmentation of a large, global databases are performed by dividing the database horizontally, vertically or both. In order to enable distributed database systems to work efficiently, these fragments have to be allocated across the available sites in such a way that reduces communication cost. This paper presents a new efficient data re-allocation model for replicated and non-replicated constrained DDBSs by bringing a change to data access pattern over sites. This approach assumes that the distribution of fragments over network sites was initially performed according to a properly forecasted set of query frequency values that could be employed over sites. Our model proposes a plan to re-allocate data fragments based on communication costs between sites and update cost values for each fragment. The re-allocation process will be performed based on selecting the maximal update cost value for each fragment and deciding on the re-allocation accordingly. empirical results showed that the proposed technique will effectively contribute in solving dynamic fragments re-allocation problem in the context of a distributed relational database systems.