Database management program and recording medium

• US 20030120689A1
• Filed: 04/09/2002
• Published: 06/26/2003
• Est. Priority Date: 12/21/2001
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Ajisawa, Jo, Sekiya, Shuji, Yamanaka, Minoru
• Granted Patent: US 7,376,678 B2
• Time in Patent Office: Days
• US Class Current: 707/205
• CPC Class Codes: G06F 16/21 Design, administration or maintenance of databases
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99956 File allocation

Abstract

A database management program capable of restoring a use management book indicating allocation/non-allocation of data to individual unit storage regions, without the need to perform physical initialization at the time of reinitialization. When the database is initialized, all allocation flags provided in the use management book and indicative of allocation/non-allocation of data to the respective unit storage regions are set to a non-allocated state, and the value of an initialization counter indicative of the number of times the database has been initialized is updated (S2). Each time data is allocated to one of the unit storage regions in the database, the allocation flag in the use management book corresponding to the data-allocated unit storage region is set to an allocated state, and the value of the initialization counter is set as an allocation-timed counter value associated with the data-allocated unit storage region (S3).

Claims

1. A database management program for managing allocation/non-allocation of data to individual unit storage regions of a database by means of a use management book,

wherein the database management program causes a computer, when the database is initialized, to set all of allocation flags provided in the use management book and indicative of allocation/non-allocation of data to the respective unit storage regions to a non-allocated state, and to update a value of an initialization counter indicative of a number of times the database has been initialized, and

causes the computer, each time data is allocated to one of the unit storage regions in the database, to set the allocation flag in the use management book corresponding to the data-allocated unit storage region to an allocated state, and to set the value of the initialization counter as an allocation-timed counter value associated with the data-allocated unit storage region.

2. The database management program according to claim 1, wherein the database management program further causes the computer, when content of the use management book has been destroyed,

to compare each of the allocation-timed counter values set in the database in association with the respective unit storage regions with the value of the initialization counter,

to set, to the allocated state, the allocation flags associated with those unit storage regions whose allocation-timed counter values coincided with the value of the initialization counter as a result of comparison, and to set, to the non-allocated state, the allocation flags associated with those unit storage regions whose allocation-timed counter values did not coincide with the value of the initialization counter, thereby to restore the use management book.

3. The database management program according to claim 1, wherein, when the database is to be initialized, a determination is made as to whether or not the database is in a state before physical initialization, and only if the database is in the state before physical initialization, the database is physically initialized.

4. The database management program according to claim 3, wherein a state flag is provided which is indicative of an initialization state of the database, and

the database management program causes the computer, when a data structure of the database has been defined, to set the state flag to a structure-defined state, and

causes the computer, if the state flag indicates the structure-defined state when the database is to be initialized, to physically initialize the database on concluding that the database is in the state before physical initialization, and to set the state flag to an initialized state upon completion of the physical initialization.

5. The database management program according to claim 1, wherein the database includes a plurality of databases for storing data in sequence while being switched, and while data is stored in one database, other databases in which data has been stored are backed up and initialized, respectively.

6. A computer-readable recording medium having a database management program recorded thereon for managing use/nonuse of individual unit storage regions of a database by means of a use management book,

wherein the database management program causes a computer, when the database is initialized, to set all of allocation flags provided in the use management book and indicative of allocation/non-allocation of data to the respective unit storage regions to a non-allocated state, and to update a value of an initialization counter indicative of a number of times the database has been initialized, and

causes the computer, each time data is allocated to one of the unit storage regions in the database, to set the allocation flag in the use management book corresponding to the data-allocated unit storage region to an allocated state, and to set the value of the initialization counter as an allocation-timed counter value associated with the data-allocated unit storage region.

7. A database server for managing use/nonuse of individual unit storage regions of a database by means of a use management book, comprising:

non-allocation flag setting means for setting, when the database is initialized, all of allocation flags provided in the use management book and associated with the respective unit storage regions to a non-allocated state;

initialization counter updating means for updating, when the database is initialized, a value of an initialization counter indicative of a number of times the database has been initialized;

allocated-state setting means for setting, each time data is allocated to one of the unit storage regions in the database, the allocation flag in the use management book corresponding to the data-allocated unit storage region to an allocated state; and

allocation-timed counter value setting means for setting, each time data is allocated to one of the unit storage regions in the database, the value of the initialization counter as an allocation-timed counter value associated with the data-allocated unit storage region.

8. A database management method for managing use/nonuse of individual unit storage regions of a database by means of a use management book,

wherein, when the database is initialized, all of allocation flags provided in the use management book and indicative of allocation/non-allocation of data to the respective unit storage regions are set to a non-allocated state, and a value of an initialization counter indicative of a number of times the database has been initialized is updated, and

each time data is allocated to one of the unit storage regions in the database, the allocation flag in the use management book corresponding to the data-allocated unit storage region is set to an allocated state, and the value of the initialization counter is set as an allocation-timed counter value associated with the data-allocated unit storage region.