JPH0612307A - Storage system for history after data base update - Google Patents

Abstract

PURPOSE:To eliminate the need to save an after-update history file on a mag netic tape in a data base system which samples and stores an after-update history for a recovery from a fault. CONSTITUTION:When the data base is updated, a before-update history is stored to a before-update history file 6 and the after-update history is stored in the after-update history file 81. Before the before-update history file 6 becomes full, an update determining process is performed and the before-update history file 6 is cleared. When the after-update history file 81 becomes full, the after- update history file 81 is switched to a file 82 and the data base which is previously copied to a stand-by data base file 3 is updated with the after-update history file 81. The after-update history files 81 and 82 are used alternately to repeat said processes. In case of a fault. the stand-by data base file 3 is restored by using the before-update and after-update history files 6 and 81 (82).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a database post-update history storage system, and more particularly to a database post-update history storage system for collecting and storing post-update history and recovering in the event of a database failure.

[0002]

2. Description of the Related Art Conventionally, this kind of database post-update history storage system stores the post-update history consisting of the update location and time information and the post-update data in the post-update history file when updating the database. However, a plurality of updated history files are sequentially used. When one updated history file overflows, it is stored in another updated history file, and the updated history stored in the overflowed updated history file is saved and accumulated on the magnetic tape. When all prepared update history files overflow, it returns to the first update history file and continues to output while writing the previously recorded information. The database is restored from the history after all these updates.

[0003]

In the conventional database post-update history storing method described above, it is necessary to save the post-update history of the overflowed post-update history file to the magnetic tape, and especially in the 24-hour non-stop operation of the database. There is a problem that a great burden is placed on the operator when performing.

[0004]

SUMMARY OF THE INVENTION A database update history storage method of the present invention is a database update history storage method for storing a database file update history and performing recovery in the event of a database file failure. A spare database file that is a copy of a database file, a history file before update, two history files after update, a database update means for updating the database and confirming the update by determining the frequency, and when updating by this database update means The pre-update history is stored in the pre-update history file, and the pre-update history storage means for clearing the pre-update history file upon confirmation and the post-update history for the update by the database updating means are designated in the post-update history file. Updated history case stored in one And means performs designation switched to the other when one of the updated history file is full,
After-update history file switching means for updating the backup database file with a full after-update history, and updating when the database file fails, the before-update history of the before-update history file is stored in the after-update history file being stored. And a database recovery means for recovering the failed database file by recovering the spare database file by using the post-history file.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention.
The embodiment shown in FIG. 1 includes a spare database creating means 1, a database file 2, a spare database file 3, a database updating means 4, a pre-update history storing means 5, a pre-update history file 6, a post-update history storing means 7, and 2 pieces. It is configured to include an updated history file group 8 having updated history files 81 and 82, an updated history file switching means 9, a preliminary database updating means 10, an updated history file restoring means 11, and a database restoring means 12. It

The spare database creating means 1 copies the database file 2 and creates a spare database file 3
To create. The database updating means 4 updates the database file 2 according to the request of the database user, and also carries out a process of confirming the update. The pre-update history storage means 5 collects the pre-update image and stores it in the pre-update history file 6 when the database file 2 is updated by the database update means 4. The updated history storage means 7 collects the updated image and stores it in the updated history file in the updated history file group 8 when the database file 2 is updated by the database updating means 4. The updated history file switching unit 9 switches the updated history file used when one updated history file overflows to another updated history file. Preliminary database updating means 10
Reads the updated history from the updated history file that overflowed when the updated history file was switched to another updated history file, and
To update. The post-update history file recovery means 11 reads the pre-update history from the pre-update history file 6 when the system is restarted after the system goes down, and retrieves the post-update history in the post-update history file in an invalid state due to the system down. to correct. The database recovery unit 12 updates the updated history file group 8 when the system is restarted after the system goes down.
This is for restoring the backup database file 3 by reading the updated history from the updated history file in the above and updating the database file.

FIG. 2 is a diagram showing an example of contents of the database file 2, the pre-update history file 6, the post-update history file group 8, and the spare database file 3 at the time of each process for explaining the process of FIG. The column of update status 201 of the database file shows the value of the data in the database file 2 and the update process. The column of the storage status 202 of the pre-update history file shows the pre-update history stored in the pre-update history file 6. The column of the storage status 203 of the updated history file group indicates the updated history file 8
The updated history stored in 1 and 82 is shown for each file. Update status of spare database file 2
The column 04 shows the data value in the preliminary database file 3 and the updating process.

Next, the processing of FIG. 1 will be described with reference to FIG. First, before the use of the database is started, the spare database creating means 1 copies the database file 2 to create the spare database file 3 in response to a request from the database user. FIG. 2 (1) shows this state. If the use of the database is started and the data A is rewritten to B by the database updating means 4, when A is rewritten to B, the pre-update history storage means 5 collects the pre-update data A and records the pre-update history. Store in file 6. The updated history storage means 7 collects the updated data B and stores it in the updated history file 81. FIG. 2 (2) shows this state. Next, the data B is updated by the database updating means 4.
When B is rewritten to C, the pre-update history storage unit 5 collects the pre-update data B and stores it in the pre-update history file 6. The updated history storage means 7 collects the updated data C and stores it in the updated history file 81. 2 (3) shows this state. Next, if it is assumed that the database update means 4 has performed processing to confirm the update, the pre-update history storage means 6 discards the pre-update history in the pre-update history file 6. FIG. 2 (4) shows this state. Next, assuming that the data C is rewritten to D by the database updating means 4, when C is rewritten to D, the pre-update history storage means 5 collects the pre-update data C and stores it in the pre-update history file 6. To do. The updated history storage means 7 collects the updated data D and stores it in the updated history file 81. FIG. 2 (5) shows this state. Next, assuming that the data D is rewritten to E by the database updating means 4, when the D is rewritten to E, the pre-update history storage means 5 collects the pre-update data D and stores it in the pre-update history file 6. To do. If the updated history file 81 cannot be written because the updated history file 81 overflows when the updated history storage unit 7 tries to store the updated data E, the updated history file switching unit 9 uses it. The updated history file is switched to the updated history file 82. Here, the updated history storage means 7 stores the updated data E in the updated history file 81. The preliminary database updating means 10 reads the updated histories B, C, and D from the updated history file 81 and updates the preliminary database file 3. 2 (6) shows this state.
Next, assuming that the data E is rewritten to F by the database updating means 4, when E is rewritten to F, the pre-update history storage means 5 collects the pre-update data E and stores it in the pre-update history file 6. To do. Updated history storage means 7
Collects the updated data F and updates the history file 8
Store in 2. FIG. 2 (7) shows this state.
Next, if it is assumed that the database updating means 4 has performed processing to confirm the update, the pre-update history storage means 6
Discards the pre-update history in the pre-update history file 6.
FIG. 2 (8) shows this state. Next, assuming that the data F is rewritten to G by the database updating means 4, when F is rewritten to G, the pre-update history storage means 5 collects the pre-update data F and stores it in the pre-update history file 6. To do. The updated history storage means 7 collects the updated data G and stores it in the updated history file 82. (9) in FIG. 2 shows this state. Next, it is assumed that the data G is rewritten to H by the database updating means 4. When G is rewritten to H, the pre-update history storage means 5
Collects the data G before update and records the history file 6 before update
To store. The updated history data is stored in the updated history storage means 7.
Supposing that the updated history file 82 overflows and the updated data H cannot be written, the updated history file switching means 9 sets the updated history file to be used in the updated history file 81. Switch. The updated history storage means 7 stores the updated data H in the updated history file 81. The preliminary database updating means 10 uses the updated history files 82 to update the updated history files E, F,
G is read and the preliminary database file 3 is updated.
FIG. 2 (10) shows this state. Next, it is assumed that the system down of the electronic computer occurs due to the failure of the storage medium of the database file 2. When the system is restarted, the post-update history file recovery means 11 reads the pre-update history from the back of the pre-update history file 6 and stores it in the post-update history file 81 as the post-update history. That is, the pre-update history G is read and stored as the post-update history in the post-update history file 81, and then the pre-update history F is stored as the read-after-update history in the post-update history file 81. After that, the pre-update history in the pre-update history file 6 is discarded. FIG. 2 (11) shows this state. Next, the database recovery means 12 reads the updated history from the updated history file 81 and updates the preliminary database file 3.
As a result, the data in the preliminary database file 3
Finally, the data F is restored to the data F when the update confirmation processing was performed. FIG. 2 (12) shows this state.

After that, the database user uses the spare database creating means 1 to copy the spare database file 3 to the database file 2 to make a new database file 2 and restart the use of the database.

[0011]

As described above, according to the present invention, the pre-update history file that stores the pre-update history and the two post-update history files that store the post-update history during the update confirmation process that is intermittently executed. Then, copy the database file, and if one of the updated history files overflows,
By providing a spare database file that is updated when switching to a table and enabling recovery in the event of a failure,
There is an effect that it is not necessary to save the updated history to the magnetic tape, and the work load on the operator can be reduced especially in the 24-hour non-stop operation.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing the contents of each file in the processing example of the embodiment of FIG.

[Explanation of symbols]

 1 Preliminary database creating means 2 Database file 3 Preliminary database file 4 Database updating means 5 Pre-update history storage means 6 Pre-update history file 7 Post-update history storage means 8 Post-update history file group 9 Post-update history file switching means 10 Pre-database update Means 11 Update history file recovery means 12 Database recovery means 81, 82 Update history files

Claims (1)

[Claims] 1. A backup database file in which a database file is copied at the time of system startup in a database update history storage method in which the updated history of the database file is stored and the database file is restored when a failure occurs in the database file. , Two updated history files, a database updating means for updating the database and fixing the update by setting a frequency, and a pre-update history file is stored in the before-update history file for updating by the database updating means A pre-update history storage means for clearing the pre-update history file, a post-update history storage means for storing the post-update history in a designated one of the post-update history files upon updating by the database updating means, and the post-update history When one of the files is full the other Switching history file switching means for switching the backup database file to the full backup history file, and updating the pre-update history file of the pre-update history file when a failure occurs in the database file. A database update history storage method comprising: a database recovery unit that recovers the spare database file and recovers the failed database file by using the updated history file stored in the subsequent history file.