Context-sensitive mobile database summarisation

Abstract

In mobile computing environments, as a result of the reduced capacity of local storage, it is commonly not feasible to replicate entire datasets on each mobile unit. In addition, reliable, secure and economical access to central servers is not always possible. Moreover, since mobile computers are designed to be portable, they are also physically small and thus often unable to hold or process the large amounts of data held in centralised databases. As many systems are only as useful as the data they can process, the support provided by database and system management middleware for applications in mobile environments is an important driver for the uptake of this technology by application providers and thus also for the wider use of the technology. One of the approaches to maximize the available storage is through the use of database summarisation. To date, most strategies for reducing data volumes have used compression techniques that ignore the semantics of the data. Those that do not use data compression techniques adopt structural (i.e. data and use-independent) methods. In this paper, we outline the special constraints imposed on storing information in mobile databases and provide a flexible data summarisation policy. The method works by assigning a level of priority to each data item through the setting of a number of parameters. The paper discusses some policies for setting these parameters and some implementation strategies.