The Impact of Data Placement Strategies on Reorganization Costs in Parallel Databases

In this paper, we study the data placement problem from a reorganization point of view. EEective placement of the declustered fragments of a relation is crucial to the performance of parallel database systems having multiple disks. Given the dynamic nature of database systems, the optimal placement of fragments will change over time and this will necessitate a reorganization in order to maintain the performance of the database system at acceptable levels. This study shows that the choice of data placement strategy can have a signiicant impact on the reorganization costs. Until now, data placement heuristics have been designed with the principal purpose of balancing the load. However , this paper shows that such a policy can be beneecial only in the short term. Long term database designs should take reorganization costs into consideration while making design choices.