US 6,983,277 B2
Method and system of database management for replica database
Kota Yamaguchi, Yamato (Japan); Shigetoshi Hayashi, Fujisawa (Japan); Junko Katsumata, Yokohama (Japan); Taichi Ishikawa, Yokohama (Japan); and Hiroshi Yamakawa, Yokohama (Japan)
Assigned to Hitachi, Ltd., Tokyo (Japan)
Filed on Jun. 26, 2002, as Appl. No. 10/184,246.
Claims priority of application No. 2001-192171 (JP), filed on Jun. 26, 2001.
Prior Publication US 2002/0198899 A1, Dec. 26, 2002
Int. Cl. G06F 17/30 (2006.01)
U.S. Cl. 707—8 7 Claims
OG exemplary drawing
 
1. A data processing unit including a database management system operating on an external storage unit provided with multiple storage areas for storing data, a multiple write mechanism allowing multiple writes of same data, a multiple write cancellation mechanism separating multi-written areas at a desired time to allow independent reading and writing as different control areas, and a physical copy mechanism that allows copying of data stored in the multiple storage areas, the data processing unit comprising:
a first data synchronizing system for writing in a data cache, and then to the multiple storage areas in the external storage unit, unwritten data, and for delaying writing updated data to the multiple storage areas;
a first data synchronization canceling system for restarting an update of the data under control of the first data synchronizing system;
a second data synchronizing system for erasing all data in the data cache when all transactions in progress are completed, and for temporarily prohibiting access by a newly generated transaction while the erasing is occurring; and
a second data synchronization canceling system for restarting data access under control of the second synchronizing system.