Database system management method, database system, database device, and backup program

Abstract

A method manages a database system that includes a first database device whose memory content in a storage area is changed based on a command designated through a network from any business terminal device, and a second database device for storing the same memory content as the first database device as a backup. The method makes the first database device execute: creating and storing a logical log that correlates a command content with a memory content in the storage area every time the process is executed; creating a physical log that correlates a position information about the portion that is changed by the process, the memory content after changing by the process, and a class of the process every time the process is executed; and storing command specifying information that specifies the command corresponding to the physical log with the corresponding physical log every time each physical log is created.

Description

DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 shows a system configuration of a database system of an embodiment,

FIG. 2 is a block diagram of a control device in a primary center under a normal condition,

FIG. 3 is a functional configuration diagram to describe a process to create a recovery log file and a differential log file,

FIG. 4 is a flowchart showing the flow of a recovery log file writing process,

FIG. 5 is a table showing examples of recovery logs,

FIG. 6 is a flowchart showing the flow of a differential-log-I/O-buffer copy process,

FIG. 7 is a flowchart showing the flow of a differential-log-file-writing process,

FIG. 8 is a functional configuration diagram about a function to create and save both a recovery log and a differential log in a conventional original database device,

FIG. 9 is a flowchart showing the flow of a process to write a differential log into a differential log I/O buffer,

FIG. 10 is a flowchart showing the flow of a writing request process to a differential-log-file-writing process task, and

FIG. 11 is a flowchart showing the flow of a differential-log-file-writing process.

Claims

1. A database system management method that manages a database system that includes a first database device whose memory content in a storage area is changed based on a command designated through a network from any business terminal device, and a second database device for storing the same memory content as said first database device as a backup, said method making said first database device execute steps comprising: creating and storing a logical log that correlates a command content with a memory content that is changed by a process in said storage area every time the process is executed according to each command;creating a physical log that correlates a position information about the portion that is changed by the process in the storage area, the memory content after changing by the process, and a class of the process every time the process is executed according to each command; andstoring command specifying information that specifies the command corresponding to the physical log with the corresponding physical log every time each physical log is created.

2. The database system management method according to claim 1, further comprising sending said logical log to said second database device.

3. The database system management method according to claim 2, wherein said second database device updates the memory content based on said logical log received from said first database device.

4. A database system that includes a first database device whose memory content in a storage area is changed based on a command designated through a network from any business terminal device, and a second database device for storing the same memory content as the first database device as a backup, said first database device comprising: a logical-log-creation section for creating a logical log that correlates a command content with a memory content that is changed by a process in the storage area every time the process is executed according to each command;a logical-log-storage section for storing said logical log created by said logical-log-creation section;a physical-log-creation section for creating a physical log that correlates a position information about the portion that is changed by the process in the storage area, the memory content after changing by the process, and a class of the process every time the process is executed according to each command;and a physical-log-storage section for storing command specifying information that specifies the command corresponding to the physical log with the corresponding physical log every time each physical log is created.

5. A backup program making a computer function as means comprising: a data storage means for changing a memory content in a storage area of a first storage device based on a command designated through a network from any business terminal device;a logical-log-creation means for creating a logical log that correlates a command content with a memory content that is changed by a process in the storage area of said first storage device every time the process is executed according to each command;a logical-log-storage means for storing the logical log created by said logical-log-creation means into a second storage device;a physical-log-creation means for creating a physical log that correlates a position information about the portion that is changed by the process in the storage area of said first storage means, the memory content after changing by the process, and a class of the process every time the process is executed according to each command; anda physical-log-storage means for storing command specifying information that specifies the command corresponding to the physical log with the corresponding physical log into a third storage device every time each physical log is created.