Finnegan, Henderson, Farabow, Garrett & Dunner
Distributed database management system for retrieving data files from databases selected based upon retrieval time
 A distributed database management system includes a plurality of computers, each including a database for storing data files to be processed. The plurality of computers are interconnected by communication lines. Each computer has stored data file names, and corresponding address area and location information for all databases, and measures data file retrieval time from the databases. A retrieval time memory section stores data file retrieval times corresponding to the address areas of data stored in the databases. A retrieval time prediction section retrieves the data file retrieval times for data files corresponding to a data file name requested by a user when the requested data file is stored in at least two databases, utilizing stored data file retrieval times and corresponding address areas and location information on where the data file is stored. A data retrieval optimization section selects the database location information and the address area associated with the requested data file name according to the retrieval result by the retrieval time prediction section, and retrieves the requested data file from the appropriate database according to the location information and address area. The system can also register input data files according to a desired retrieval time. 
Kabushiki Kaisha Toshiba
Y G Y Y Y G
Y10S G06F Y10S Y10S Y10S G06F
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Yojiro Miho Nobuhiro Koichi
Morimoto Muranaga Kato Sekiguchi