A Collaborative Query Processing Method for a Database Broadcasting System

M. Kashita, T. Terada, T. Hara, M. Tsukamoto, S. Nishio (Japan)


Database broadcasting, ECA rule, Query processing, Mobile environment


In a database broadcasting system, the server periodically broadcasts contents of database to mobile clients such as portable computers and PDAs. In this system, there are two possible methods for query processing: one is that a client stores all data which are necessary for processing a query and then processes it locally, and the other is that the server processes a query and broadcasts the query result to the query issue client. However, a client cannot get query results when the disk space of the client is not enough for query processing in the former method or when overfull queries are issued in the latter method. In this paper, to resolve these problems, we propose a method which pro cesses a query by collaboration of the server and clients. In our method, the server adds identifiers to tuples appearing in the query result. Thus, the client can store only necessary tuples by referring to the identifiers. In addition, the server broadcasts rules which define the client’s behavior for re ceiving data, and then, the query results are constructed on the client by using the rules. In this way, clients can get query results efficiently.

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