Consistent Query Plan Generation in Secure Cooperative Data Access

In this paper, we consider an environment where a group of parties have their own relational databases, and provide restricted access to other parties. In order to implement desired bushiness services, each party defines a set of authorization rules over the join of basic relations, and the accessible information is constrained by these rules. However, authorization rules are given based on the business requirements and the enforcement issues of the rules may not have been taken into consideration. In this paper, we propose an algorithm to check the rule enforceability for each given authorization rule, and also present mechanisms to generate a query execution plan for an authorized query which is consistent with the authorization rules. As finding the optimal query plan can be very difficult, we propose an algorithm to generate efficient query plans. In addition, we compare the generated query plans with the optimal query plans through case studies. The results show the effectiveness of our approach.