Data Placement in a Shared - Nothing Parallel Deductive Database

Until recently most research into parallel databases has focussed on relational database systems. Nevertheless, there is growing interest in more powerful alternative systems such as deductive databases. Several rule handling strategies have been developed to incorporate deductive capabilities into parallel database systems. However, in a shared-nothing environment, the performance of a rule handling strategy depends largely on the effectiveness of the data placement strategy adopted in the system. Poorly distributed data can lead to higher loads and/or load imbalance and hence higher cost when executing a query. This paper describes a weightbased data placement strategy which provides improved performance for rule handling in a shared-nothing main memory database system. The main idea behind the data placement strategy is to exploit relation co-location as much as possible for join operations, while distributing evenly the relation fragments across the processors using their weights.