The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 17, 2004
Filed:
Sep. 19, 2000
Itaru Nishizawa, Koganei, JP;
Shigekazu Inohara, Yokohama, JP;
Nobutoshi Sagawa, Koganei, JP;
Akira Shimizu, Yokohama, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A query processing system in which a virtual table to enable multiple mapping to a plurality of databases is provided in a data processing system to receive a query from an application program and partial replicas as copies of part of the data in the virtual table is prepared in storage so that the whole or part of a query can be processed using the partial replicas. For query units which cannot be processed using the partial replica, means to select an appropriate distributed join method and optimization to push down query processing to real databases as far as possible are used. The system allows transparent access to multiple different real databases according to access conditions without changing the column to be accessed in the virtual table or switching the virtual table, thereby eliminating the need to create a new application for each newly developed service.