JPH113263A - Replica database matching device and replica database matching method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a replication database consistency device and a replication database consistency method that guarantee data consistency of a replication database system even when data is updated in a plurality of database systems. SOLUTION: When updating a database of a self-site, a reflection information of the self-site is created by adding header information having information used for checking the consistency of the update information to collected post-update information, At the same time, the reflection information of the own site is transferred to another site, and when the reflection information of the other site is received from the other site, the reflection information of the other site is stored in the own file. Store the information in a dedicated file, check the consistency of the reflection information in the dedicated file of the own site, select the reflection information necessary to maintain the consistency, and use the reflection information necessary to maintain the consistency. Update the database.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a replication database matching device, a replication database matching method, and a recording medium used in the same in a replication database system.

[0002]

2. Description of the Related Art A conventional replica database system is a system in which a replica of a master database at a site is created at another site so that consistency between the master database and the replica is maintained.

In a conventional duplicate database system, in order to maintain consistency between the master database and the replica, for example, a communication circuit is periodically updated from a site having the master database to a site having the replica. Via the Internet and the copy has been updated with the updated content.

For example, in a company with a head office, the head office is selected as a site having a master database,
A branch is selected as the site with the replica. In this case, there is no need to access the master database at the head office via the communication circuit every time the customer database is accessed at the branch, for example, resulting in advantages such as reduced access time and reduced communication costs. It is so popular.

In the replica database reflecting device and replica database reflecting method described in Japanese Patent Application Laid-Open No. 8-77053, additional information is added to updated data obtained after updating a database in a source database (master database). By creating reflection information, transferring the reflection information to the replication destination database (replication), and performing reflection processing directly from the reflection information to the replication destination database,
It enables low-load replication between databases with different physical structures.

[0006]

However, the conventional replica database system has been designed based on the idea that the number of master databases is one and that the content of the master database should be reflected on the replica of another site. If we proceed from the conventional basic structure of classifying databases into a master database and its replicas and try to treat multiple databases as equivalent, that is, if we want to update data in any database, ,
When the conventional replication update method (replication database reflection method) is applied to each database, if the same record of the same table in multiple databases is updated with different values at the same time, each reflection information is copied There is a possibility that the data is transferred to the destination database device and changed by the reflection information of each other.

For example, referring to FIG. 5, two database systems (database system A (reference numeral 501) and database system B (reference numeral 50)
Assume that a character string "SUN" is stored in a certain item of a certain record (505a and 505b) of a certain table in the duplicate database system composed of 2)). The database system A (501) updates this item value to "MON" (507), and the database system B (502) simultaneously updates this item value to "TUE".
(508), the replica database reflecting devices (503 and 5) in each database system
04) transfers “MON” and “TUE” as reflection information to the other replication database reflection devices (504 and 503), respectively, and the replication database reflection device (504 and 503) updates the data based on the reflection information. I do. Therefore, the value of this item is changed to "TUE" or "MON" in each database system, and data inconsistency occurs between the duplicate database systems, and the consistency cannot be maintained.

Accordingly, the present invention provides a replication database consistency device and a replication database consistency method that guarantee data consistency in a plurality of database systems even when data is updated in the plurality of database systems in a replication database system. The purpose is to do.

[0009]

SUMMARY OF THE INVENTION A replicated database coordinator according to the present invention is a replica database coordinator used in a replicated database system in which a database is updated at each site. A replication update history information file, which is a set of reflection information to which header information having information used to check information consistency is added, and the header information is added to the updated information when updating the database of the own site. The reflection information of the own site is created, and the reflection information of the own site is stored in the replication update history information file of the own site, and the reflection information of the own site is transferred to another site. When the reflection information is received from another site, the reflection information of the other site is copied to the replication update history of the own site. The consistency of the reflection information replication device stored in the replication information history file and the reflection information in the replication update history information file of the own site, and selecting the reflection information necessary to maintain the consistency; And a reflection information reflection device that updates the database of the own site with reflection information necessary to maintain the information.

[0010] The duplicate database matching device according to the present invention is characterized in that the header information is an update time, a generation system name, a record number, an item, pre-update data, and post-update data.

[0011] The replication database consistency method according to the present invention is a replication database consistency method used in a replication database system in which a database is updated at each site. The reflection information of the own site is created by adding header information having information used for checking the consistency, and the reflection information of the own site is stored in the replication update history information file of the own site. A step of transferring the reflection information of the site to another site, and a step of storing the reflection information of the other site in the replication update history information file of the own site when the reflection information of the other site is received from the other site; Investigate the consistency of the reflection information in the replication update history information file of the own site,
Selecting the reflection information necessary for maintaining the consistency and updating the database of the own site with the reflection information necessary for maintaining the consistency.

Further, in the replication database matching method according to the present invention, the header information is an update time, a generation system name, a record number, an item, pre-update data, and post-update data.

[0013] A recording medium according to the present invention is characterized by recording a program for causing a computer to execute the above-mentioned duplicate database matching method.

Further, the recording medium according to the present invention is a copy update set which is a set of reflection information obtained by adding header information having information used for checking the consistency of update information to updated information collected at the time of updating a database. A history information file is recorded.

Further, in the recording medium according to the present invention, the header information includes an update time, a generation system name, a record number,
It is characterized by items, pre-update data, and post-update data.

[0016]

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

FIG. 1 is an overall configuration diagram of a replication database system including a replication database matching device according to the present embodiment. The database system A (reference numeral 120)
The database system is at a certain site, and the database system B (reference numeral 121) is a database system at another site. The replication database matching device of the present invention is a reflection information replication device (101 and 102)
And the reflection information reflection device 103 and the copy update history information files (104 and 105).

The reflected information copying apparatus 101 stores, in the updated information 113 obtained after updating the database (DB) 111 and recorded in the update history information file 112, an update time, a generated system name, a record number, an item, and data before update. And a function of creating reflection information 106 to which header information composed of updated data is added and storing the reflection information 106 in the copy update history information file 104.

Reflection information copying device (101 and 102)
Has a function of copying the reflection information (106 and 107) of the copy update history information file (104 and 105) between database systems. However, FIG. 1 illustrates only copying in the direction from the reflection information duplication device 101 to the reflection information duplication device 102.

Further, the reflection information reflection device 103 has a function of checking the data of the reflection information 107 of the copy update history information file 105 to check whether there is any inconsistency in the update history. If necessary to resolve the inconsistency, the reflection information 107 transferred from the other database system 120 may be used.
The database 11 of the own database system 121
4 has a function of executing the update.

Next, the operation of the present embodiment will be described in detail with reference to FIG.

The application 122 is the database 1
11 (S201), the database management system (DBMS) 110 outputs post-update information 113 for recovery to the update history information file 112 after updating the database (S202). Here, the reflection information duplication device 101 of the duplication database coordination device updates the post-update information 1 of the update history information file 112 for recovery.
13, the reflection information 106 is created and stored in the reflection information file (replication history information file) 104 (S20).
3). Next, it is determined whether the reflection information needs to be transferred to the copy destination by checking the checkpoint (S20).
4). Checkpoints are set when new reflection information is created, and when the transfer of reflection information is completed,
It is reset when it is no longer necessary to transfer. The reflection information duplication device 101 transfers the reflection information 106 to be transferred to the reflection information duplication device 102 of the duplication destination database matching device (S205).

The reflection information replication device 102 of the replication database matching device of the replication destination database system 121 receives the transferred reflection information (S206) and stores (merges) it in the replication update history information file 105 (S20).
7). The reflection information reflection device 103 checks the consistency of the reflection information 107 in the copy update history information file 105 (S208). The reflection information reflection device 103 acquires the reflection information 107 in which no inconsistency was detected in the result of the consistency check, and recovers the reflection information 107 due to the inconsistency.
Is created (S209). The reflection information reflection device 103
The database is updated from the reflection information 107 to be reflected in the database 114 (S210). In this case, the reflection information reflection device 103 does not create the reflection information from the post-update information generated when the database is updated. This is to prevent a new consistency check operation from occurring.

For the sake of explanation, it has been described that the original data is updated in the database system 120 and the data in the database system 121 is updated accordingly. This data update and the data update reflecting the data update are mutually performed, and the actual configuration of each database system is a combination of the components of the database system 120 and the database system 121.

[0025]

Next, an embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 3, database system A
At (reference numeral 301), there is a record 303a having a record number of 001 whose value of the "day of the week" item is "SUN", and the same record 303b also exists in the database system B (reference numeral 302).

Here, the database system A (reference numeral 3)
When the “day” item of the record 303a whose record number is “001” is changed to “MON” (312), the reflection information duplication device 306 of the database system A (reference numeral 301) The reflection information 001 (reference numeral 310) is created. Reflection information duplication device 306 of database system A (reference numeral 301)
Transfers the added reflection information 001 (reference numeral 310) to the reflection information replication device 307 of the database system B (reference numeral 302) in order to copy the replication update history information file 310 in the database system B (reference numeral 302). .

The reflection information duplication device 307 of the database system B (reference numeral 302) transmits the reflection information 001 (reference numeral 31).
0b) is received and stored in the copy update history information file 308. The reflection information reflection device 315 of the database system B (reference numeral 302) examines whether the added reflection information 310c and the existing reflection information are inconsistent.
The reflection information is checked by checking the consistency between the data before change and the data after change for each item in the order of the update time.
In the figure, in the reflection information 000 (reference numeral 309), the item “day of the week” is changed from “SAT” to “SUN”, and the reflection information 00
Since 1 is changed from “SUN” to “MON” at 310 (code 310), the change has continuity and no inconsistency is detected.
When the consistency check of the reflection information is completed normally, the reflection information reflection device 31 of the database system B (reference numeral 302).
5 is the reflection information 0 from the copy update history information file 308.
01 (reference numeral 310c), and the record 3 of which the record number of the database system B (reference number
The "day of the week" item of 03b is changed from "SUN" to "MON".

FIG. 4 is a diagram for explaining the operation and processing method of the processing device when the reflection information passes each other.
“SUN” is set as an initial value in the item of the day of the week in the records (303a and 303b) with the record number 001 of the database system A (reference numeral 301) and the database system B (reference numeral 302). Here, the day of the record (303a) having the record number 001 of the database system A (reference numeral 301) is “MON” (3
12) is updated. At the same time, database system B
The record with the record number of (001) (001) (001)
The day of the week 03b) is updated to “TUE” (313).
The reflection information duplication device 306 of the database system A (reference numeral 301) and the reflection information duplication device 307 of the database system B (reference numeral 302) respectively include the reflection information 001.
(Reference numeral 310a) and reflection information 002 (reference numeral 311a). Next, the database system A (reference numeral 301)
The reflection information duplication device 306 transmits the reflection information 001 (reference numeral 3).
10a) to the reflection information duplication device 307 of the database system B (reference numeral 302), and similarly, the reflection information duplication device 307 of the database system B (reference numeral 302) transmits the reflection information 002 (reference numeral 311a) to the database system A.
It is transferred to the reflection information duplication device 306 (reference numeral 301).
Both reflection information copying devices (306 and 307) store the reflection information received from the other party in the replication update history information files (305 and 308).

Next, the reflection information reflection devices (314 and 31)
5) Copy update history information files (305 and 308)
Investigate the integrity of In this case, although the updated data of the “day of the week” item is updated to “MON” in the reflection information 001 (reference numeral 310), the reflection information 002 (reference numeral 3) is used.
The data before update of 11) is not “MON” but “SU”.
N ", a contradiction has occurred.

The reflection information reflection device 314 of the database system A (reference numeral 301) receives the reflection information 001 (reference numeral 31).
0) and the reflection information 002 (reference numeral 311) are determined to have occurred at the same time, and the “day of the week” item of the record 001 is corrected to an appropriate value. As a way to choose the right value,
It is possible to select a “validate last updated value” method, “validate first updated value”, and the like. Here, a method of “validating the last updated value” is adopted. Therefore, the database system A (reference numeral 3)
01) is applied to the reflection information 002.
(311) is reflected and the record number is 0
The day of the record 01 (reference numeral 303a) is set to “TUE”.

The reflection information reflection device 315 of the database system B (reference numeral 302) detects the same inconsistency, but does not perform the reflection processing because the reflection information 002 (reference numeral 311) is valid.

[0033]

As described above, according to the present invention, any database can be obtained by merging the copy update history information files acquired by each database system and checking the consistency of the reflection information in the files. Since the data of the system can be kept in the same state, the uniqueness of the data in the duplicate database system is completely guaranteed.

[Brief description of the drawings]

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

FIG. 2 is an operation sequence flow of the present invention.

FIG. 3 is an embodiment of the present invention.

FIG. 4 is an embodiment of the present invention.

FIG. 5 is a configuration diagram of a replication database system including a conventional replication database reflection device.

[Explanation of symbols]

101, 102 Reflected information copying device 103 Reflected information reflecting device 104, 105 Replication update history information file 106, 107 Reflected information 110, 113 Database management system (DBMS) 111, 114 Database (DB) 112 Update history information file 113 Updated information 120, 121 Database system

Claims (7)

[Claims] In a replication database coordinator used in a replication database system in which a database is updated at each site, information used for checking the consistency of the update information is included in updated information collected at the time of updating the database. A replication update history information file that is a set of reflection information to which the own header information is added; and, when updating the database of the own site, creating the reflection information of the own site by adding the header information to the post-update information. When the reflection information of the site is stored in the replication update history information file of the own site, the reflection information of the own site is transferred to another site, and when the reflection information of the other site is received from another site, the other A reflection information replication device that stores the reflection information of the site in the replication update history information file of the own site; Investigating the consistency of the reflection information in the replication update history information file, selecting the reflection information necessary for maintaining the consistency, and using the reflection information necessary for maintaining the consistency, the database of the own site. And a reflection information reflecting device for updating the replication database. 2. The replication database matching device according to claim 1, wherein the header information is an update time, a generation system name, a record number, an item, pre-update data, and post-update data. 3. A replication database consistency method used in a replication database system in which a database is updated at each site, in order to investigate the consistency of the updated information in the updated information collected when the database of the own site is updated. Attach header information having information to be used to create reflection information of the own site, store the reflection information of the own site in the replication update history information file of the own site, and simultaneously copy the reflection information of the own site to another site. Transferring the reflection information of the other site to the replication update history information file of the own site when receiving the reflection information of the other site from the other site; and Investigate the consistency of the reflection information in the history information file, select the reflection information necessary to maintain the consistency, and maintain the consistency Updating the database of the own site with the reflection information necessary for the operation. 4. The replication database matching method according to claim 3, wherein the header information is an update time, a generation system name, a record number, an item, pre-update data, and post-update data. 5. A recording medium recording a program for causing a computer to execute the replication database matching method according to claim 3 or 4. 6. A copy update history information file which is a set of reflection information obtained by adding header information having information used for checking consistency of update information to updated information collected at the time of updating a database. Recording medium characterized by the above-mentioned. 7. The recording medium according to claim 1, wherein the header information is an update time, a generation system name, a record number, an item, pre-update data, and post-update data.