Providing freshness guarantees for outsourced databases

Abstract

Database outsourcing becomes increasingly attractive as advances in network technologies eliminate the perceived performance difference between in-house databases and out-sourced databases, and price advantages of third-party database service providers continue to increase due to economy of scale. However, the potentially explosive growth of database outsourcing is hampered by security concerns, namely data privacy and query integrity of outsourced databases. While privacy issues of outsourced databases have been extensively studied, query integrity for outsourced databases has just started to draw attention from the database community. Currently, there still does not exist a solution that can provide complete integrity. In particular, previous studies have not examined the mechanisms for providing freshness guarantees, that is, the assurance that queries are executed against the most up-to-date data, instead of just some version of the data in the past. Providing a practical solution for freshness guarantees is challenging because continuously monitoring data's up-to-dateness is expensive. In this paper, we perform a thorough study on how to add freshness guarantees over proposed schemes (including authenticated data structure-based and probabilistic-based approaches) to provide integrity assurance. We implement our solutions and perform extensive experiments to quantify the cost. Our experiment results show that we can provide reasonable tight freshness guarantees without sacrificing much performance. Copyright 2008 ACM.