A query processing method for mobile client on a database broadcasting system

摘要

In the recent evolution of wireless communication technology, there has been an increasing interest in the broadcast database system where a server periodically broadcasts contents of a database to mobile clients such as PDAs. There are two methods to process queries in the broadcast database system; one is that a client stores in his/her disk all data that are necessary in producing the result and then processes it locally, and the other is that a server processes a query and broadcasts the query result to a client. However a client cannot properly obtain query results when the disk space of the client is small in the former method or when queries are issued frequently in the latter method. In this paper, to resolve this problem, we propose a method where a server and a client process a query in collaboration in the broadcast database system. In this method, a server adds indentifiers to tuples appearing in the query result when the server receives a query from a client. By referring to the identifiers, the client can store only necessary tuples. In addition, the server creates rules to define the behavior of the client and broadcasts them, By using these rules, the query results are automatically issued on the client. As a result, clients can obtain query results efficiently in this method.