International Journal of Applied Information Systems (IJAIS)
In the large scale distributed environment, the query optimization presents new problems because of the data unavailability, the estimations inaccuracies and environment instability. In this paper, the authors address the sub-optimality of executions plans caused by these problems. They propose to extend the join algorithms based on mobile agents in order to correct the sub-optimality. This extension allows the join to change their execution site. Indeed, the mobile agent executing a join adapts to changes in characteristics of the execution environment (e.g. network bandwidth, available memory) and responds to the estimations inaccuracies (e.g. size of intermediate relations).