JP2002318717A - Database system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a database system, with which backup is enabled through a simple work process and the work quantity of a system manager can be reduced, in the database system for performing multiversion system simultaneous transaction execution control. SOLUTION: While a backup start/end instructing means 20 instructs backup start/end, even when a plurality of transactions update the latest versions, a database managing system 70 guarantees the consistency of files comprising a database as a backup object so that a base page system, logic log system or full page system can be backed up by a file backup means 10 not through the database managing system 70.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a database system for backing up files by file backup means not via a database management system.

[0002]

2. Description of the Related Art In a database management system, as information for canceling or re-executing a certain operation content of a certain transaction, conventionally, for each transaction operation, information for canceling the operation and information for re-execution have been used. The information has been stored as a set. This stored content is called a log.

[0003] Logs are classified as follows according to the type of information to be stored.

A logical log records what operation has been performed and what operation should be performed to cancel the operation. For example, "Table A
Delete row with row identifier 10 "and" Table A has row identifier 1
0, insert a row with a, b, c as column values ".

A physical log records images before and after updating pages in a file. Compared with the logical log, the amount of information to be recorded is enormous, but the execution and re-execution of the operation are simple because the operation is simply a page operation.

[0006] The logical and physical log (physiological lo
g) Record what operations have been performed on logical files such as record files and B-tree files that make up tables and indexes, and what operations should be performed to cancel the operations. Record the content of the operation on the page as necessary. The amount of information to be recorded is between the logical log and the physical log. Compared to the logical log, it is easier to determine whether the operation recorded in the log should be applied to the page.

Recovery from a medium failure is performed by re-executing (REDO) or canceling (UNDO) operations after that point on the basis of these logs from a consistent database secured at a certain point in time. . When recovering from a media failure, return the consistent database that was backed up, and then perform the operations performed from the time when the backup was performed until just before the failure occurred, by reading the log and using
And recover.

[0008] The log is recorded in WAL (Write Ahead Loggi
ng) It is necessary to follow the protocol. That is, when writing the buffering content of the update operation to the database to the disk, the log of the operation must be written to the disk.

Although a system failure can be similarly recovered,
Performing the checkpoint processing during the operation of the system can reduce the recovery time.

The checkpoint process is performed in the following procedure.

1. Suspend the execution of a transaction and the acceptance of a new transaction. 2. By writing out all buffered database updates that have not yet been written to disk, the consistency of the files that make up the database is guaranteed at this point. 3. Each time a transaction updates a page for the first time after checkpoint processing, the page image before the update is recorded in the physical log. Discard the contents recorded in this physical log. 4. Execution of the transaction and reception of a new transaction are resumed.

During checkpoint processing, all buffered database updates that need to be written out must be written out to disk, and in some cases the execution and acceptance of transactions must be stopped for a very long time. No. To reduce this time, the following fuzzy checkpoint processing has been devised.

1. Suspend the execution of a transaction and the acceptance of a new transaction. 2. Writes out all buffered database updates that have not been written out to disk yet that were not written out during the previous fuzzy checkpoint process. 3. Remember any buffered database updates that have not yet been written to disk. This is the next fuzzy checkpoint processing. Used in. 4. All contents recorded from the end of the fuzzy checkpoint process two steps before the physical log to the start of the immediately preceding fuzzy checkpoint process are discarded. 5. Execution of the transaction and reception of a new transaction are resumed.

In the fuzzy checkpoint, only the updated contents of the buffered database that need to be written out and have not been written out in the immediately preceding fuzzy checkpoint are written out to the disk. In comparison, the processing time is more likely to be reduced.

When a normal checkpoint process is performed, recovery from a system failure is performed as follows. 1. By writing back the page image before update recorded in the physical log to the page updated after the immediately preceding checkpoint processing, the state of the database at the end of the checkpoint processing is returned. 2. The operation after the checkpoint processing of the transaction executed at the time of the immediately preceding checkpoint processing is re-executed while reading the log. 3. Cancel transactions that have not been completed at the time of failure while reading the log.

When the fuzzy checkpoint processing is performed, the contents of the database updated before the start of the two previous checkpoint processings are surely written to the disk, but the contents after that are guaranteed. Not done.
Therefore, in the case of normal checkpoint processing, the state is first returned to the state immediately after the immediately preceding checkpoint processing, but in the case of fuzzy checkpoint processing, the state is returned to the state immediately after the end of the previous two checkpoint processing.

Since the checkpoint process can be performed in a shorter time as compared with the backup of the database, the checkpoint process can be periodically performed at a considerable frequency during the operation of the system.
Therefore, compared to the recovery processing from the backup contents, the number of operations to redo-undo is reduced, and the recovery time is shortened.

As a method of backing up a database, a method has been proposed in which a file backup means does not pass through a database management system in a database system which performs multi-version transaction simultaneous execution control.

[0019]

SUMMARY OF THE INVENTION The present invention relates to a method for backing up a file by means of a file backup means which does not pass through a database management system in a database system for controlling the simultaneous execution of transactions in a multi-version system. It focuses on the problems.

That is, in this method, the file storing the base page, version page, and version map area to be backed up may contain the contents updated by the transaction being executed when the backup is started. To recover a consistent database simply by restoring what was backed up, transactions that reference the recovered database must be able to ignore the latest version updated by the transaction in progress at the start of the backup. No. Therefore, 1. It is necessary to limit the number of transactions that can update the latest version simultaneously to one. If a transaction updates the latest version and another transaction allows the version to be updated before the transaction ends, the current transaction will ignore the updated version at the start of the backup and start the backup. In some cases, updates to transactions that have been completed are ignored, resulting in inconsistent database. 2. To ignore the latest version updated by the transaction being executed at the start of the backup, the following a. b. Any information must be included. a. For each latest version, each is updated and a transaction identifier (also referred to as a transaction ID) representing the transaction being executed.
And a permanent value) b. The transaction identifier of each transaction being executed at the start of the backup, and the transaction identifier of the last updated transaction for each latest version

In the above, a. Needs to delete the stored transaction identifier for each version updated by the transaction every time the transaction ends, which is expensive in terms of management. B. Is a. Instead of reducing the management cost, the storage area cost increases.

The present invention has been made in view of such a problem, and is a database system for performing multi-version type transaction simultaneous execution control, which can perform backup in a simple work process, and An object of the present invention is to provide a database system that can reduce the amount of work.

[0023]

According to the present invention, which achieves the above object, it is possible to directly access and back up files constituting a database.

That is, a first aspect of the present invention is a database system for performing a transaction concurrent execution control of a multi-version system, which generates a new version by a copy source update system. Even if multiple transactions are updating the latest version, the database management system guarantees the consistency of the files that make up the database being backed up, so that the file can be backed up without using the database management system. This is a database system characterized in that it is possible to perform backup in a system.

According to a second aspect of the present invention, there is provided a database system for performing concurrent execution control of a multi-version system, wherein a new version is generated by a copy destination update system. Even if the transaction of the latest version is updated, the database management system guarantees the consistency of the files constituting the database to be backed up.
This is a database system characterized by being capable of base page backup.

According to a third aspect of the present invention, there is provided a database system for performing a transaction concurrent execution control of a multi-version system, wherein a new version is generated by a copy destination update system. Even if the transaction of the latest version is updated, the database management system guarantees the consistency of the files constituting the database to be backed up.
This is a database system characterized in that logical log backup is possible.

According to a fourth aspect of the present invention, there is provided a database system for performing concurrent execution control of a multi-version system, wherein a new version is generated by a copy destination update system. Even if multiple transactions update the latest version, the database management system guarantees the consistency of the files that make up the database being backed up. This is a database system characterized in that it is possible to perform backup in a system.

[0028]

Embodiments of the present invention will be described below in detail.
First, software and hardware of the embodiment will be described.

FIG. 1 is a configuration diagram of software of a database system according to the present invention. It is constituted by means having the following functions.

File backup means 10 The file 50 constituting the database is directly accessed without going through the database management system 70, and the file is backed up.

Backup start / end instructing means 20 Instructs the database management system 70 to start or end the backup.

Inquiry input / output means 30 accepts an inquiry request and outputs the result.

Query executing means 71 The query from the query input / output means 30 is executed using the database file access means 72, and the result is returned. In addition, an instruction from the backup start / end instruction means 20 is executed. In addition, logs according to the content of the query,
It is recorded using the log file access means 75.

The transaction control means 74 starts and ends a transaction in response to a request from the inquiry input / output means 30. For the transaction to be aborted, all the operations performed by the transaction are canceled using the log file access means 75. In addition, simultaneous execution control of transactions is performed by a multiversion method.

Checkpoint control means 73 Performs checkpoint processing periodically.

Database file access means 72 Provides an interface for operating the files 50 constituting the database, and buffers input / output to / from a disk. Writing of the buffered contents to the disk is performed in cooperation with the log file access unit 75 in accordance with the WAL protocol.

The database file 50 stores data objects in the database.

Log file access means 75 Provides an interface for operating the log file 60, and buffers input / output to / from the disk.

The log file 60 stores information necessary for re-executing and canceling the operation performed in the transaction. The start and end of the transaction and the fact that the checkpoint process has been performed are also stored.

FIG. 2 is a diagram showing hardware of a computer system configured for database processing. It is composed of the following devices.

A computer used by a user of the terminal 100 system to input a query request to the database management system 70, which is a portion indicated by a dotted line in FIG. 1, and output a query result. Yes, the database file 50 recorded on the hard disk 210 on the server 200 is queried, and the contents are
It is also a computer used to write to 0.

In general, the terminal 100 is provided with a pointing device such as a keyboard 150 and a mouse 160 for inputting an inquiry request, and a display 170 for displaying an inquiry result. The terminal 100 includes a CPU 120, a memory 130, and a hard disk 110, and is capable of executing a software program. In the terminal 100, the inquiry input / output unit 3 of FIG.
0, backup start / end instruction means 20 and file backup means 10 are executed as programs. When the tape drive 140 is provided, the backup file 40 can be recorded.

Server 200 A computer for performing an inquiry process in response to an inquiry request input from the terminal 100 and returning the result to the terminal 100. In response to a request from the terminal 100 to obtain a file to be backed up, It is also a computer used to return the contents of the file to the terminal 100 or to write the contents of the file to the tape drive 140 in response to a request from the terminal 100 to write a file to be backed up to a tape.

The terminal 100 and the server 200 are connected by a communication network 300 described later. Server 200
Is a CPU 220, a memory 230, a hard disk 210
And a software program is executable. In the server 200, a query execution unit 71, a database file access unit 72, and a transaction control unit 74 constituting the database management system 70 indicated by a dotted line in FIG. 1 are executed as programs. The database file 50 is recorded on the hard disk 210. When the tape drive 240 is provided, the backup file 40 can be recorded. In some cases, a tape drive for recording backup contents is provided.

Communication network 300 is a transmission line connecting terminal 100 and server 200.
Generally, it is realized by cable, and the communication protocol is TC
P / IP is used. However, the terminal 100 and the server 2
As long as the communication protocol with 00 is the same, a wireless LAN without using a cable or a network using broadcast waves may be used.

In the present invention, when the minimum configuration unit of the version in the multi-version simultaneous execution control system is a page in a file constituting the database, the database has the following area as shown in FIG. , A version page area, a version map area, and a logical log area. Each area is composed of a plurality of files. Even if the minimum constituent unit is not a page, if it is any unit below the file, it can be dealt with by replacing the page in the following description with it.

In the base page area, the latest version of the page is stored when a new version is generated by the copy source update method, and the oldest version of the page is stored when the new version is generated by the copy destination update method. Is done.

In the version page area, when a new version is generated by the copy source update method, the old version of a certain page, that is, the page image before the update of the page to be written, is generated by the copy destination update method. Then, a new version of a certain page, that is, an updated page image of a page to be written is stored.

The version map area stores a page identifier, a base page, and the correspondence between a plurality of versions of the page in the version page area. The information required by the multi-version simultaneous execution control system to be used, such as the storage location for each version, is stored.

The logical log area records a logical log as information for canceling or re-executing an operation on the database. Since information indicating the recording order is also recorded in the logical log, the logical log can be read in the recording order or in the reverse order.

When a transaction updates the latest version of a certain page, the database file access means 72 copies the latest version to the version page area if any of the following conditions is satisfied.

1. This version has never been updated since it was created. 2. No currently running transaction has updated this version. 3. This version is the first update since the previous checkpoint process is completed.

When the latest version is copied, in the case of the copy source update method, the version of the copy source is updated to become a new latest version. Conversely, in the case of the copy destination update method,
The copy destination version is updated to the new latest version. At this time, condition 3. If so, the original latest version can be used as a physical log to recover a page to its state at the time of the last checkpoint when recovering from a failure.

In the logical log area, in addition to information on cancellation and re-execution of operations on the database, the fact that the following operations have been performed is recorded as a logical log for backup and recovery.・ Start of checkpoint processing ・ End of checkpoint processing ・ Start of backup ・ End of backup ・ Start of synchronization ・ End of synchronization

Here, in the case of the copy destination update method, synchronization means that a version that is not referred to by a current transaction or a transaction started in the future is discarded from a version page area, and a version page relating to a certain page is discarded. The overwrite of the oldest version that can be referenced in the area with the oldest unreferenced version in the base page area of the page. Naturally, the version map area is accordingly updated according to the new correspondence between the base page of the page and the version page area. For example, in FIG. 3, page 1 has four versions and the storage location a
And the versions of x and x are synchronized when they are not referenced, the version of storage location a is overwritten with the version of storage location y, which is the oldest version that can be referenced, and the versions of storage locations x and y are discarded. .

The backup differs depending on which area of the above-mentioned area belongs to which file is to be backed up. Base system, second. 2. logical log method, It works like a full file system.

First. Base page method This method backs up all files in the base page area. In the base page area, the latest version of the page is stored in the case of the copy source update method, and the oldest version of the page is stored in the case of the copy destination update method. In the case of the copy source update method, it is the latest version existing at the time of backup of the database, and in the case of the copy destination update method, it is the oldest version.

The backup is performed in the following steps 1 to 3.

1. Backup start / end instruction means 20
Instructs the database management system 70 to start backup. The query execution means 71 in the database management system 70 receiving the instruction performs the following processing.
This process is different between the copy source update method and the copy destination update method.

First, the case of the database management system 70 for generating a new version by the copy source update method will be described. The processing of a to c is performed.

A. The log file access means 75 is caused to record a logical log indicating the start of backup in the logical log area.

B. Database file access means 7
2 instructs writing of the updated contents of the database file in the base page area that have not been written to the disk.

C. Even if a file that makes up the base page area is updated by a transaction that updates during backup, the database file access unit 72 ensures that the contents to be backed up are consistent.
Is instructed to perform one of the following a, b, and c, or a combined process.

A. Prohibits writing of updated buffering contents to disk. In FIG. 4, when updating the version of the page 1 at the file storage location a in the base page area, the version is first copied to the file storage location x of the version page area, and then the base page area is updated. Updates to the version page and version map area may be written to disk, while updates to the base page area are only on the buffer and not written to disk.

B. If the updated file has not been copied, the updated buffering contents are copied first, and then written to the copy destination without changing the copy source. In FIG. 5, when updating the version of the page 1 at the file storage location a in the base page area, the version is first copied to the file storage location x of the version page area, and then the base page area is updated. The updated contents of the base page, the version page, and the version map area may be written to the disk. However, for the base page area, the updated file is copied and then written to the copy destination file.

C. The updated buffering content is not written to the updated file, and if a temporary file has not been generated, it is generated and written to the temporary file. In FIG. 6, when updating the version of the page 1 at the file storage location a in the base page area, the version is first copied to the file storage location x of the version page area, and then the base page area is updated. The updated contents of the base page, the version page, and the version map area may be written to the disk. However, for the base page area, a temporary file is generated and then written to the file.

In the case of a database management system that generates a new version according to the copy destination update method, the following operations are performed.

A. It instructs the transaction control means 74 to stop the start of the synchronization.

B. If the above-mentioned synchronization is being executed, the process waits for the end. Or give up the backup.

C. The log file access means 75 is caused to record a logical log indicating the start of backup in the logical log area.

D. Database file access means 7
2 instructs writing of the updated contents of the database file in the base page area that have not been written to the disk.

By these processes, the unwritten update contents are reflected on the disk at the start of the backup in the database file of the base page area to be backed up, and the update is prohibited until the backup is completed. Is guaranteed.

In the case of 1. Following the processing of 2. And 3. Is performed.

2. The file backup means 10 copies all files constituting the base page area to a non-volatile medium such as a tape.

3. Backup start / end instruction means 20
Instructs the database management system 70 to end the backup. The query execution means 71 in the database management system 70 receiving the instruction performs the following processing.
This process differs between the copy source update method and the copy destination update method.

In the case of the copy source update method, the following processes a and b are performed. a. The log file access unit 75 records a logical log indicating that the backup has been completed in the logical log area. b. For the database file access means 72,
The following a, b, and c processes are instructed.

B. If writing of the updated buffering contents to the disk is prohibited, the ban is released. B. If the updated buffering contents have been written to the copy destination file, the copy source file is discarded, or the copy destination file is overwritten on the copy source file. C. If the updated buffering contents have been written to a temporary file, the contents of the temporary file are written to a file to be actually written.

In the case of the copy destination update method, the following processes a to c are performed. a. The log file access unit 75 records a logical log indicating that the backup has been completed in the logical log area. b. It instructs the transaction control means 74 to restart the stopped synchronization. c. Initiate a synchronization that was received during the backup but was not started.

Second. Logical log method This method backs up all files in the base page area and logical log area. As described above, the logical log area stores information for canceling and re-executing a transaction's operation on the database. If information stored in the base page area is added, backup is performed in this manner. In the case of the copy source update method, the latest version that exists at the time of backup of the database is used, and in the case of the copy destination update method, the oldest version and the transaction executed immediately before the backup for that version It becomes contents of.
Therefore, in the case of the copy source update method, there is no point in using this method.

The backup is performed according to the following steps 1 to 3.

1. Backup start / end instruction means 20
Instructs the database management system 70 to start backup. The query execution means 71 in the database management system 70 that has received the instruction performs the following processes a to f.

A. It instructs the transaction control means 74 to stop the start of synchronization. b. If synchronization is in progress, wait for its termination. Or give up the backup. c. The log file access means 75 is caused to record a logical log indicating the start of backup in the logical log area. d. For the database file access means 72,
Instructs writing of the updated contents of the database file of the base page that have not been written to the disk. e. It instructs the log file access unit 75 to write the updated contents of the log file in the logical log area that have not been written to the disk. f. Even if the files that make up the logical log area are updated by a transaction that updates during backup,
In order to assure the consistency of the contents to be backed up, the following a. B. C. Is instructed to perform any one of the processes described above.

B. Prohibits writing of updated buffering contents to disk. B. If the updated file has not been copied, the updated buffering contents are copied first, and then written to the copy destination without changing the copy source. C. The updated buffering content is not written in the updated file, but is generated and written to the temporary file if a temporary file has been generated.

With these processes, the unwritten update contents are reflected on the disk at the start of the backup in the database file of the base page area to be backed up and the log file of the logical log area, and updates that lose the contents are prohibited. Therefore, the consistency of the backup contents is guaranteed.

2. The file backup means 10 copies all files constituting the base page and the logical log area to a non-volatile medium such as a tape.

3. Backup start / end instruction means 20
Instructs the database management system 70 to end the backup. The query execution means 71 in the database management system 70 receiving the instruction performs the following processes a to d.

A. The log file access unit 75 records a logical log indicating that the backup has been completed in the logical log area. b. The following a.
B. C. Is instructed. I. If writing of the updated buffering contents to the disk is prohibited, the ban is released. B. If the updated buffering contents have been written to the copy destination file, the copy source file is discarded, or the copy destination file is overwritten on the copy source file. C. If the updated buffering contents have been written to a temporary file, the contents of the temporary file are written to a file to be actually written. c. It instructs the transaction control means 74 to restart the stopped synchronization. d. Initiate a synchronization that was received during the backup but was not started.

Third. All file system base page, version page, version map,
This method backs up all files in the logical log area. The version page and the version map area store information for obtaining an old version in the case of the copy source update method and a new version in the case of the copy destination update method from the version stored in the base page. This method backs up the latest version that exists at the time of backup of the database in the case of the copy source update method, and performs the normal checkpoint processing with the oldest version in the case of the copy destination update method. If the checkpoint processing immediately before the start of the backup and the fuzzy checkpoint processing are performed, the latest version at the end of the checkpoint processing two times before the start of the backup. Therefore, like the logical log method, in the case of the copy source update method,
There is no point in using this method.

The backup is performed in the following steps 1 to 3.

1. Backup start / end instruction means 20
Instructs the database management system 70 to start backup. The query execution means 71 in the database management system 70 that has received the instruction performs the following processes a to j.

A. It instructs the transaction control means 74 to stop the start of synchronization. b. It instructs the checkpoint control means 73 to stop the start of the checkpoint processing. c. If synchronization is in progress, wait for its termination. Or give up the backup. d. If the checkpoint process is being executed, the process waits for the end. Or give up the backup. e. The log file access means 75 is caused to record a logical log indicating the start of backup in the logical log area. f. For the database file access means 72,
It instructs writing of the updated contents of the database file in the base page, the version page, and the version map area that are not written to the disk. g. It instructs the log file access unit 75 to write the updated contents of the log file in the logical log area that have not been written to the disk. h. Even if the files that make up the version page area are updated by a transaction that updates during the backup, the area used at the start of the backup in the version page area is Instructs not to reuse even if unused. In the version map area to be backed up, the correspondence between a plurality of versions of a certain page at the start of the backup is stored. When reused, backup versions may appear to correspond to different page versions or the order in which the versions were generated may be inconsistent, resulting in inconsistent backup content. is there. i. Even if the files that make up the version map area are updated by a transaction that updates during backup, the base file copy source update must be performed on the database file access means in order to guarantee the consistency of the contents to be backed up Similar to the processing for the base page area of the method, the following a. B. C. Is instructed to perform any one of the processes described above.

B. Prohibits writing of updated buffering contents to disk. B. If the updated file has not been copied, the updated buffering contents are copied first, and then written to the copy destination without changing the copy source. C. The updated buffering content is not written in the updated file, but is generated and written to the temporary file if a temporary file has been generated.

J. Even if a file that makes up the logical log area is updated by a transaction that updates during the backup, the log file access unit 75 must be
i. The same instruction is performed.

By these processes, the unwritten update contents are reflected on the disk in the base page, version page and version map area database file to be backed up, and the log file in the logical log area at the start of the backup, and the contents are stored in the disk. Prohibiting losing updates ensures the integrity of the backup content.

2. The file backup means 20 copies all files constituting the base page, version page, version map, and logical log area to a non-volatile medium such as a tape.

3. Backup start / end instruction means 20
Instructs the database management system 70 to end the backup. The query execution means 71 in the database management system 70 receiving the instruction performs the following processes a to f.

A. The log file access unit 75 records a logical log indicating that the backup has been completed in the logical log area. b. For the database file access means 72,
The following a. B. C. Is instructed.

B. If writing of the updated buffering contents to the disk is prohibited, the ban is released. B. If the updated buffering contents have been written to the copy destination file, the copy source file is discarded or the copy destination file is overwritten on the copy source file. C. If the updated buffering contents have been written to a temporary file, the contents of the temporary file are written to a file to be actually written.

C. For the log file access means 75, b. The same instruction is performed. d. It instructs the transaction control means 74 to restart the stopped synchronization. e. Instruct the checkpoint control means 73 to restart the start of the checkpoint process. f. Initiate a synchronization that was accepted during backup but not started.

[0100]

According to the present invention, in a database system using a database management program that uses a multi-version method for simultaneous execution control, a database backup is performed while a plurality of transactions update the latest version, and a backup dedicated to the database management program is performed. Allows you to directly access and back up the files that make up the database, not programs. As a result, the database system can perform backup with a simple work process even in a normal operation state in which a general user is executing multiple transactions, reducing the workload of the system administrator. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a software configuration diagram of a database system embodying the present invention.

FIG. 2 is a hardware configuration diagram of the database system.

FIG. 3 is a conceptual diagram of a page of a minimum configuration unit of a version, and is a diagram illustrating synchronization in a copy destination update method.

FIG. 4 is a conceptual diagram of a page of a minimum configuration unit of a version, and is a diagram illustrating a backup process in a base page method according to the present invention.

FIG. 5 is a diagram for explaining a backup process in the base page method of the present invention.

FIG. 6 is a diagram illustrating a backup process in the base page method according to the present invention.

[Explanation of symbols]

 10; file backup means 20; backup start / end instructing means 30; query input / output means 40; backup file 50; database file 60; log file 70; database management system 71; query execution means 72; Point control means 74; transaction control means 75; log file access means 100; terminal 200; server 300;

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsuya Ikeda 1-3-6 Nakamagome, Ota-ku, Tokyo Stock inside Ricoh Company (72) Inventor Takuya Hiraoka 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Ricoh Company (72) Inventor Junichi Yamagata 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Company (reference) 5B082 DE06 GA14 GB07

Claims (4)

[Claims] 1. A database system for performing multi-version type transaction simultaneous execution control,
A file that constitutes a database to be backed up by the database management system even if multiple transactions are updating the latest version while the backup start and end are instructed in a new version created by the copy source update method A database system characterized in that base page backup can be performed by a file backup means that does not go through a database management system by guaranteeing the consistency of a database. 2. A database system for performing multi-version type transaction simultaneous execution control,
A file that constitutes a database to be backed up by the database management system, even if multiple transactions have updated the latest version while the backup start and end are instructed in a new version created by the copy destination update method A database system characterized in that a base page backup can be performed by a file backup means that does not go through a database management system by guaranteeing the consistency of the database. 3. A database system for performing multi-version type transaction simultaneous execution control,
A file that constitutes a database to be backed up by the database management system, even if multiple transactions have updated the latest version while the backup start and end are instructed in a new version created by the copy destination update method A database system wherein logical log backup can be performed by a file backup means that does not go through a database management system by guaranteeing the consistency of the database management system. 4. A database system for performing multi-version type transaction simultaneous execution control,
A file that constitutes a database to be backed up by the database management system, even if multiple transactions have updated the latest version while the backup start and end are instructed in a new version created by the copy destination update method A database system characterized in that backup of all file systems is enabled by file backup means that does not go through a database management system by guaranteeing the consistency of the file system.