JPH052517A - Data base journal control system - Google Patents

Abstract

PURPOSE:To safely use a data base system over a long period by surely executing the switching of journal files for writing data base journal records. CONSTITUTION:At the time of detecting overflow when a journal record output means 3 is writing records in a previously set journal file #1, a journal file automatic swapping means 4 switches the working journal file #1 to another journal file #2. When a forced switching instruction is applied based upon a command outputted from a console 14, the working file #1 is forcedly switched by a journal file forced swapping means 6. Immediately before the switching, the writing file #1 is saved to a magnetic file 15 by a journal file saving means 5 and the file #1 is released.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a database journal control system, and more particularly to a method of controlling a journal of a database system in information processing.

[0002]

2. Description of the Related Art Conventionally, a database system is equipped with a journal control mechanism for outputting an updated image as a journal record to a journal file when the database file is updated in preparation for a failure. Also, if the magnetic disk device that stores the database file has a media failure, save the database file before update to another media, and recover the database file by the collected journal file up to the point immediately before the failure. It has a recovery control mechanism.

By the way, the journal file can be stored in a magnetic disk device or a magnetic tape device. When the journal file is stored on the magnetic tape device, the magnetic tape device is occupied and used during operation of the database system, the journal record is output on the magnetic tape, and if the first magnetic tape overflows, The first and third volumes are sequentially switched, and processing is continued.

When the journal files are stored on the magnetic disk device, a plurality of journal files are prepared in advance. The journal record is output to the prepared journal file, and at the time of overflow, switching to the next journal file is performed automatically or compulsorily by the operator's switching instruction.

In any case, the journal file switching is performed in the order of the journal files prepared in advance. When all the prepared journal files are used, a means for returning to the top journal file and cyclically using it is provided. In this case, it is necessary to save the journal file for which journal record output has been completed beforehand to another file before cyclically using it.

Any of the database journal control methods using the magnetic tape device or the magnetic disk device prevents the operation of the database system from being stopped at the time of overflow of the journal file. In particular, it is a very important technology in a recent database system in which the operation takes a long time.

The above-mentioned conventional database journal control system has the following problems. That is, in the method using the magnetic tape device, the magnetic tape device is always occupied during the operation of the database system, and it is necessary to prepare the magnetic tape device only for the journal of the database system.

Further, in the method using a magnetic disk device, which has appeared as a technique replacing the magnetic tape device, the journal files are switched in a prepared order. Therefore, when the operator detects the overflow of the journal file in advance and forcibly switches the journal file with a command, and the journal file to be switched next is not prepared for some reason, the journal file Cannot switch.

This is a situation that is unlikely to occur normally, but it can occur with a fairly high probability when the database system is operated for a long time. The following are possible statuses in which the journal file at the switchover destination has not been prepared.

After collecting the journal record, the contents of the journal file are not saved in another file.

The area of the journal file of the magnetic disk device is used for another purpose, and the file is not prepared.

A magnetic disk device having a journal file has a medium failure and is not recovered.

Whether or not the journal file is automatically switched is not known unless the usage status of the journal file is confirmed by a command. Immediately save the used journal file when the switching is performed. If the journal file does not have sufficient capacity and the journal file does not have sufficient capacity, it will return to the beginning of the journal file before saving the used journal file.

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a database journal control system capable of safely operating a database system for a long time by always switching journal files. ..

[0015]

The database journal control system according to the present invention comprises a plurality of journal files for storing database journal records, a means for writing the journal records to a predesignated journal file, and a journal file being written. A means to automatically switch to another journal file when overflow occurs, a means to forcibly switch the journal file being written to another journal file by an external instruction, and a means to respond to the occurrence of the journal file switching. , Means for saving the journal file being written immediately before switching.

[0016]

According to the database journal control method of the present invention, the environment of the journal file used by the journal environment setting means is set in advance, and the journal file initialization means sets the environment by the journal environment setting means. Make the file ready for output,
The journal record output means outputs the journal record to the journal file prepared by the journal file initialization means, and the journal file automatic swap means outputs to the next journal file when the journal file output means overflows the journal file being output. Switch.

Further, the journal file forced swap means forcibly switches the journal file output destination of the journal record by the journal record output means by a command, and the automatic job starting means uses the journal file forced swap means and the journal file automatic swap means. When the journal files are switched, the journal file save means is started, and this journal file save means saves the output journal files that have been switched by the journal file forced swap means and the journal file automatic swap means. Reusable.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. The database journal control system according to this embodiment includes a journal environment setting unit 1, a journal file initializing unit 2, a journal record output unit 3, a journal file automatic swapping unit 4, a journal file saving unit 5, and a journal file forcing. Swap means 6, automatic job starting means 7, application program 11, and database operation mechanism 12
, Database file 13, console 14,
Magnetic tape device 15 and journal files # 1 to # 4
It consists of and.

The journal environment setting means 1 is means for setting the journal environment in advance when collecting and operating journals in the database system, by designating the number of journal files, and by specifying the specified number of journal files. Register the catalog of. What is catalog registration?
To register the medium name and file name of the magnetic disk device to which the journal file is allocated.
In this example, the journal environment setting means 1 sets journal files # 1 to # 4 as journal files.

The journal file initialization means 2 initializes the number of journal files designated by the journal environment setting means 1. Initialization means securing a journal file area and writing control information in the first block of the journal file. In this example, the journal file initialization means 2 secures the areas of the journal files # 1 to # 4, and the control information is written in the head block.

It is not necessary to initialize the journal file by the journal file initializing means 2 for all the journal files set by the journal environment setting means 1, and the journal record output means 3 will set the journal records. Just go before you output.

The journal record output means 3 is means for outputting a journal record to the journal file prepared by the journal file initialization means 2.

Journal file automatic swap means 4
Is a means for switching the output to the next journal file when the journal file being output by the journal record output means 3 overflows.

The journal file saving means 5 is means for saving the output journal file switched by the journal file automatic swapping means 4 and the journal file forced swapping means 6 in the magnetic tape device 15 and making it available again.

Journal file forced swap means 6
Is a means for forcibly switching the journal file output destination of the journal record by the journal record output means 3 by a command entered from the console 14 by the operator.

The automatic job activating means 7 automatically activates the journal file saving means 5 when the journal file is switched by the journal file automatic swapping means 4 and the journal file compulsory swapping means 6 and causes the console 14 to operate. It is means for notifying the mount information of the magnetic tape to the magnetic tape device 15.

Next, the operation of this embodiment thus constructed will be described. Application program 11
When an update request is made to the database file 13, the database operation mechanism 12 analyzes the request and updates the database file 13. At this time, the database operation mechanism 12 notifies the journal record output means 3 of the updated state of the database file 13.

Upon receiving the notification from the database operation mechanism 12, the journal record output means 3 outputs the journal record to the first journal file among the journal files set by the journal environment setting means 1, that is, the journal file # 1. ..

The journal record output means 3 repeatedly outputs the journal record to the journal file # 1 based on the notification from the database operation mechanism 12. Journal file # 1 by output of journal record
When it detects that the file overflows, the journal record output means 3 notifies the journal file automatic swapping means 4 of the journal file switching request.

The journal automatic swap means 4 which has received the notification of the journal file switching request from the journal record output means 3 should be used next to the journal file # 1 based on the information registered in the catalog by the journal environment setting means 1. , Get catalog information of journal file # 2.

Next, the journal file automatic swap means 4 opens the journal file # 2 to make it possible to output the journal, closes the journal file # 1 and releases the resources. Subsequently, the journal file automatic swap means 4 causes the journal record output means 3
And it notifies the automatic job starting means 7 that the switching of the journal file is completed.

When the journal record output means 3 is notified by the journal automatic swap means 4 that the journal file switching is completed, it outputs the journal record to the journal file # 2.

When the automatic job starting means 7 is notified by the journal file automatic swapping means 4 that the switching is completed, the automatic job starting means 7 starts the journal file saving means 5 and provides the console 14 with the mount information of the magnetic tape on the magnetic tape device 15. Notice. This mount information notification is displayed in red on the console 14 to call the operator's attention. This notification of mount information does not disappear until the operator mounts the evacuation magnetic tape. When the operator mounts the magnetic tape on the magnetic tape device 15,
The journal file saving means 5 saves the contents of the journal file # 1 in the magnetic tape device 15.

In the above switching and saving processing, when the overflow of the journal file # 2 is detected, the contents are switched to the journal file # 3 and the contents of the journal file # 2 are saved.
To journal file # 4, and from journal file # 4 to journal file # 1.

Now, assuming that the journal record output means 3 is outputting a journal record to the journal file # 1, the journal file scheduled to be output next is the journal file # 2. At this time,
When the magnetic disk device allocating the journal file # 2 is in a state of being unusable due to a medium failure, and when another magnetic disk device does not have enough capacity to allocate the journal file # 2, the operator operates the console 14 From journal file # 3
The journal file compulsory swap means 6 is notified of the compulsory switching request to the journal file.

The journal file forced swap means 6 which receives the notification of the forced switching request from the console 14 sends the journal file # 1 to the journal record output means 3.
To output the journal record to the journal file, the catalog information of the journal file # 3 is obtained from the journal environment setting means 1, and the journal file # 3 is opened so that the journal record can be output.

Next, the journal file forced swap means 6 closes the journal file # 1 and releases the resources. When the swap of the journal files is completed, the fact is notified to the journal record output means 3 and the automatic job starting means 7.

Upon receiving the notification of the completion of switching from the journal file forced swap means 6, the journal record output means 3 transfers to the journal file # 3 in the same manner as when it receives the notification of completion of switching from the journal file automatic swap means 4. Start outputting journal records.

Upon receipt of the notification of completion of switching from the journal file forced swapping means 6, the automatic job starting means 7 causes the journal file saving means 5 to save the contents of the journal file # 1 to the magnetic tape device 15. ..

[0041]

As described above, according to the present invention, when the journal file overflows, the journal file is automatically switched to another journal file, and the journal file is forcibly switched to another journal file by an external command. By saving the journal file just before switching to a magnetic tape, etc., the journal file can be switched due to various failures of the journal file system, so that the service can be continued without stopping the database operation. effective.

It is considered that the database system will continue to provide the service for a long time in the future. Therefore, it is extremely important not to stop the operation of the database system due to the failure of the journal file. It's a big one.

[Brief description of drawings]

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

[Explanation of symbols]

 # 1 to # 4 journal file 1 journal environment setting means 2 journal file initialization means 3 journal record output means 4 journal file automatic swapping means 5 journal file saving means 6 journal file forced swapping means 7 automatic job starting means 15 magnetic tape device

Claims (1)

Claim: What is claimed is: 1. A plurality of journal files for storing database journal records, a unit for writing the journal records to a predesignated journal file, and a journal file being written overflows. Means for automatically switching to another journal file, means for forcibly switching the journal file being written to another journal file in response to an external instruction, and immediately before switching in response to the occurrence of the journal file switching. And a means for saving the journal file being written.