Partial-Replicated Dynamic Fragment Allocation in Distributed Database System

Many organizations having a number of databases may geographically distribute databases all over the world using distributed database system. One major task of distributed database is how to allocate fragments among the different sites over the network. It has the greater impact on the performance of the distributed database and the operational efficiency of the system. Nowadays, many application or invoked query from different sites where the access patterns of sites made to fragments change over time and then dynamic fragment allocation technique provides better solution than static fragment allocation technique. The dynamic fragment allocation technique migrate the fragment dynamically according to the access patterns of each fragment. This paper proposes a strategy for partial-replicated dynamic fragments allocation in distributed database system. In reallocation process, the proposed strategy reallocates the fragment with respect to read and write data volume factor. When more than one site simultaneously qualifies for fragment reallocation, it will reallocate fragment with respect to the write data volume and distance factors of respectively different sites. This algorithm will decrease the transfer cost and be faster response time of the system.