JP2000284998A - Data update control system and method and computer readable recording medium storing program for executing the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distributed data management system for holding all updated data even when the update competition of a master database is generated. SOLUTION: In a distributed data management system connected through a network 400, a replica site 200 is provided with a replica data base 260 and a local updated data base 270 which holds updated data, and the replica site 200 issues a request for the reflection of the updated data on a master database 150, and receives the updated result, and prepares the replica database 260. A master site 100 receives the request of the master update, and updates the master database 150, and transmits the updated result to the replica site 200 which issues the request for update. When data competing at the time of the master update are present, the data are registered in the master database 150 as a version to which a site ID is added so that all the updated data can be held.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data update control system, and more particularly to a data update control system for controlling data update when updating data on a master database when a master database and a replica database of the master database exist on a network. About technology.

[0002]

2. Description of the Related Art Computer systems such as personal computers and workstations are connected to a network (Loca).
l Area Network, Wide Area Network, etc.), one of the most important technologies in network computing that performs each processing while exchanging information with each other via the network. There are distributed data management systems that access databases residing on other computer systems. According to this distributed data management system, a database existing in one computer system can be shared by a plurality of computer systems. Here, a computer system having a shared database is called a database server, and a computer system accessing the shared database is called a client.

If the shared database is frequently accessed by clients, requests are concentrated on the database server, which may cause a bottleneck in the entire network. Therefore, by placing a copy of this database on the second database server, the load of access to the shared database is distributed, and the bottleneck is eliminated. Such a copy of the same database is called a replica, and making this copy is called a replication.

Here, the original shared database is called a master database, a database server having a master database is called a master site, a shared database for replication is called a replica database, and a database server having this replica database is called a replica site. I do. Therefore, the client accesses the master database at the master site or the replica database at any of the replica sites when accessing the shared database.

[0005]

Conventionally, in a distributed data management system as described above, when a client on a communication network updates a plurality of replica databases, the master database and the replica database are updated by the following method. To make the databases equivalent. Copy the contents of the master database at a certain point in time (for example, at a time interval or at the time of updating) as it is to the replica database. -Incremental update is performed by reflecting the transaction log in the master database at a certain point in the replica site. When one or both of the master database and the replica database are updated, they are mutually reflected by deciding which value of the master database or the replica database is to be left.

However, according to these conventional methods, when a database is to be updated at multiple sites, the database is updated by the update content of one of the sites in order to maintain the equivalence of the database, and other databases are updated. The problem is that updates made on the site are lost. In such a case, the user will not be able to refer to or make changes later.

In order to solve such a problem, according to the present invention, all update data is retained even when an update conflict occurs in a master database, so that a user can refer to and update data at any time. It is an object of the present invention to provide a data update control system for a distributed data management system that can be used. Furthermore, if such a system is used, the data circulating on the network becomes huge,
Another object of the present invention is to provide a data update control system that reduces the communication load on a network as much as possible.

[0008]

According to a first aspect of the present invention, there is provided a data update control system comprising one master site for holding a master database and one or more replica sites for holding a replica database which is a copy of the master database. In the distributed data management system connected via a network, the replica site requests the local update database that holds the updated data of the replica database, and reflects the updated data on the master database. A master update request unit that receives the content of the master database as an update result and creates a replica database that is a copy, and updates the master database by receiving a request from the master update request unit at the master site. Master The master update request unit of the replica site requests the content of the local update database of the replica site to update the master database to the master site, and at the master site, the master update unit Receiving the update request, updating the master database, and updating the replica database by transmitting the updated master database to the master update request unit of the replica site that has requested the update when the update is successful; It is characterized by doing so.

The data update control system according to a second aspect of the present invention is the data update control system according to the first or twelfth aspect, wherein the master database, the replica database and the local update database each include a version number. It is also characterized in that it also holds version management information in comparison with the site identification information of the replica site.

A data update control system according to a third aspect of the present invention, in the data update control system according to the second aspect, has a database of a normal version that does not hold site identification information of version management information and the site identification information. It is characterized by having a site version.

According to a fourth aspect of the present invention, in the data update control system according to the third aspect, a local update unit is provided at the replica site, and the local update unit is provided with a normal update unit for the replica database. When the version data is updated, the result is stored in the local update database, and the stored version registers a newer version than the replica version and the ID of the replica site as site identification information. .

According to a fifth aspect of the present invention, in the data update control system according to the fourth aspect, the local update unit of the replica site updates the data of the local update database. In this case, store the result in the local update database, and register the stored version with a newer version number than the original version of the updated local update database and the ID of the replica site as site identification information. It is characterized by.

According to a sixth aspect of the present invention, in the data update control system according to the third aspect, a conflict determination unit is provided in a master update unit of the master site. If the latest version of the master database at the master site is smaller than the oldest version of each data of the local update database at the replica site, it is determined to be a normal version,
Otherwise, the master update unit determines that the version is a site-added version, and when the conflict determination unit determines that the version is the normal version, the master update unit registers all the contents of the local update database in the master database as the normal version. If the version is with, the contents of the local update database is registered in the master database as a version with a site, the updated master database is transferred to the replica site where the master update was requested, and the master update request unit is It is characterized in that it is copied to the replica database and the local update database is cleared.

According to a seventh aspect of the present invention, in the data update control system according to the first or twelfth aspect, the master update request unit of the replica site sends only the data to be updated to the master site. The master database is partially updated.

The data update control system according to claim 8 of the present invention is the data update control system according to claim 1 or 12, further comprising a replica update request unit at the replica site, wherein the replica update request unit is Requesting to transfer the contents of the master database from the replica site to the master site when the local update database is empty, and replicating the master database to the replica database at the replica site. .

According to a ninth aspect of the present invention, in the data update control system according to the first or twelfth aspect, the master site does not accept requests from two or more replica sites at the same time. It is characterized by doing so.

According to a tenth aspect of the present invention, in the data update control system according to the first aspect, the master site requests the replica site to periodically operate a master update request unit. By doing so, the master database and the replica database are periodically updated.

In the data update control system according to the present invention, in the data update control system according to the first aspect, the replica site periodically operates a master update request unit to periodically operate the master update request unit. The database and the replica database are updated.

A data update control system according to a twelfth aspect of the present invention provides a network in which one master site holding a master database and one or more replica sites holding a replica database which is a copy of the master database are connected. In the distributed data management system connected via a network, the replica site includes a local update database that holds the updated data of the replica database, and a checkout request that requests the exclusive right to change the master database of the master site. A master update requesting unit for requesting to reflect the updated data to the master database, receiving the contents of the updated master database and creating a replica database as a replica, and a master database. A check-in request unit for requesting to abandon the exclusive right of the master database after the update, wherein the master site has a setting for inspecting the right to monopolize and change the master database in response to a check-out request from the replica site. Checkout department to
A master update unit that receives a request from the master update request unit and updates a master database, and an unlock unit that executes a request for abandoning the exclusive right of the master database from the replica site, wherein the replica site The check-out request unit sends a request to the master site specifying the data to be checked out, and the master update request unit sends the data of the local update database to the master site when the check-out is successful, And updates the replica database, and when the check-in request unit succeeds in updating the replica database, sends a request for waiver of the exclusive right to the master site and clears the local update database, and the master site Check out part Check-out of the data to be checked out received from the recovery site is performed, the result is sent to the replica site of the request, and the master update unit updates the data of the local update database sent thereto while updating the master database. Sending the master database to the requesting replica site, and canceling the check-out when the unlock unit receives a request from the replica site to release the exclusive right.

Further, according to a data update control method of the present invention, a network is established by connecting one master site holding a master database and one or more replica sites holding a replica database which is a copy of the master database. In the distributed data management system connected through the above, the replica site requests the local update database that holds the updated data of the replica database and the updated data to be reflected in the master database, and updates the update result. A master update request unit that receives the contents of the master database and creates a replica database that is a replica,
The master site includes a master update unit that receives a request from the master update request unit and updates a master database.The master update request unit of the replica site stores the contents of the local update database of the replica site as the Requesting a master site to update a master database, wherein at the master site the master updater receives a request for the update, updates the master database, and updates the master database upon a successful update Is transmitted to the master update request section of the replica site that has issued the update request, thereby updating the replica database.

According to a fourteenth aspect of the present invention, there is provided a computer-readable recording medium comprising one master site for holding a master database and one or more replica sites for holding a replica database which is a copy of the master database. In a distributed data management system connected via a network, the replica site requests a local update database that holds data updated to the replica database, and requests that the updated data be reflected in the master database. A master update request unit that receives the contents of the master database as an update result and creates a replica database that is a replica, and the master site receives a request from the master update request unit and updates the master database. An update unit, wherein the master update request unit of the replica site requests the contents of the local update database of the replica site to update the master database to the master site, and at the master site, the master update unit Receiving a request for update and updating the master database;
A program for updating the replica database by transmitting the updated master database to the master update request section of the replica site that requested the update when the update was successful was recorded.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation principle of the present invention will be described below using five embodiments.

(1) Overall Environment FIG. 1 is a diagram showing an operating environment of the data update control system of the present invention. The operation environment of this system includes one master site 100 that holds a master database,
One or more replica sites 200 that hold replicas of this master database and one or more clients 300 that refer to and update this database are connected in a network environment 400. Further, the use of the present system is not limited to the client 300, and the system may be used from the master site 100 or the replica site 200.

FIG. 2 shows a master site 1 on which the present invention operates.
00, replica site 200 and client 300
FIG. 3 is a diagram showing a computer hardware configuration of the computer. The input unit 1 includes a keyboard, a mouse, a touch panel, and the like, and is used for inputting information. The output unit 2 outputs various output information, information input from the input unit 1, and the like, and includes a display device, a printer, and the like.

The CPU 3 operates various programs. The memory 4 holds the program itself, and also holds information temporarily created when the program is executed by the CPU 3. The storage unit 5 holds a database, a program handled by the present system, temporary information at the time of executing the program, and the like. The medium driving means 6 is used to load a recording medium storing programs, data, and the like, read them, and store them in the memory 4 or the storage means 5. Further, it may be used for directly inputting / outputting data or executing a program. Network interface (I /
F) 7 is a master site 100, a replica site 200
And the computer of the client 300 and the network 4
This is an interface device for transmitting and receiving information on a network by interfacing with the network interface 00.

(2) Database of the present system and its use (A) Types of databases The present system holds the following three types of databases. -Master database-Replica database-Local update database The master database is one master site 100.
There is one. The data is managed by the exclusive control at the master site 100, and the data in the master database is the only correct data.

One or more replica databases exist for one master database and are held at the replica site 200. A client can search both the replica database and the local update database. In this replica database, data is periodically transferred from the master site 100 to the replica site 200. Immediately after the transfer, the contents of the master database and the replica database match, but they do not always match. When updating data at the replica site 200, the data is updated based on the contents of the replica database, and the update result is held in the local update database. The data held in the local update database is sent to the master site 100 to update the master database.

(B) Data Structure of Three Databases FIG. 3 is a diagram showing the data structure of the above three databases, and these three databases have the same data structure. The database stores version information (2
1, 22) and the main body 2 of data managed by the database
5 (FIG. 3 (a)) and a case where checkout information (23, 24) is added thereto (FIG. 3 (b)).
There is.

The version information includes a version number 21 and a site ID 22. A version number is always added to the data body 25, and when this data is updated, the version is always changed. For example, the version number is determined to start from 1 and increase by one each time it is updated sequentially. The site ID 22 is a unique identifier for identifying a replica site, and for example, a host name (src.ricoh.co.jp or the like) is used. That is, version information is added so that it can be known which site has updated the data. If there is no conflict in the version number in the master database, it is assumed to be a version that does not have a site ID, this version is called "normal version",
If there is a conflict, the version is assigned a site ID, which is referred to as a “version with site ID”.

In the following description, version information will be written as follows. Normal version: Version number Version with site ID: Version number @ Site I
D Further, the version information in the local update database is generated as follows. -Only the version with the site ID of the replica site is used.-The version number is obtained by adding 1 to the version number to which the updated data of the replica database belongs. When updating data registered in the local update database, it is assumed that 1 is added to the version number of the local update database to which the data belongs at the time.

The checkout information includes a checkout flag 23 and a site ID 24. Checkout is a request for obtaining the right to change the data in the master database. If the checkout flag 23 is "true", the user has the right to change the data, which is "false". Indicates that there is no right. Here, the site ID 24 is an identifier for identifying the replica site requested to check out. This format is the same as the site ID of the version information.

(C) Use of Version Information FIG. 4 shows the transition of the version information when the data in the master database is updated. When the version number is 1, it indicates that the master database was first generated. When the version number is 2, it indicates that the data has not been updated and has been registered as a normal version.

When the version number is 3, the data registered first becomes the normal version, and is locally updated in the version 2 replica database at the replica site, and when the master database is requested to be updated, the version is already updated. Since the number is 3, the one requested to be updated later is registered as a version with a site ID. Similarly, when the version number is 5, it means that after updating the version number 4, another update was performed separately from the two sites to the replica database having the same version number 4. ing.

FIG. 5 shows that, at the replica site, data is changed in the database having the version number 2 and is stored in the local update database. The result of updating is that the version number is 3
Is shown.

First Embodiment A first embodiment of the present invention will be described with reference to FIGS. (1) Description of Configuration Diagram FIG. 6 is a diagram for explaining the functional configuration of the first embodiment of the present invention.

The master site 100 includes a control unit 110,
It comprises a master update unit 120, a replica update unit 130, a master update request activation request unit 140, a search update unit 180, and a master database 150. The control unit 110 controls each function (the master update unit 120, the replica update unit 130, the master update request activation request unit 140, and the search update unit 180) and controls the transmission and reception of data through the network. The master update unit 120 receives the master database 150 from the replica site 200.
Process the data update request. When updating the master database 150, a conflict determination unit 125 for determining a conflict state is provided. The replica updating unit 130 processes a transfer request of the master database 150 from the replica site 200.

The master update request activation requesting unit 140 is periodically activated by time control such as a timer, and requests all the replica sites 200 to transmit an update request for updating the master database 150. The search and update unit 180 searches and updates data by exclusive control. Master database 15 upon request from client 300
Perform a data search of 0 and return the result. When updating the search result, the master database 150 is updated as a normal version. The master database 150 is the only database existing in the network, and its data is copied to the replica database at each replica site, and the replica database is searched and updated.

The replica site 200 includes a control unit 210,
Master update request unit 220, replica update request unit 23
0, local update unit 240, master update request start unit 2
50, a search unit 280, a replica database 260, and a local update database 270.
The control unit 210 controls each function (the master update request unit 220,
It controls the replica update request unit 230, the local update unit 240, the master update request activation unit 250, and the search unit 280), and controls the transmission and reception of data through the network. The master update request unit 220
Requesting that the contents of the local update database 270 be updated at the master database 150 at the master site 100, receiving the updated master database 150, replacing the replica database 260, and clearing the local update database 270. . The replica update requesting unit 230 operates when the local update database 270 is empty, requests to transmit the contents of the master database 150 of the master site 100, and replaces the replica database 260 with the received contents of the master database.

The local update unit 240 writes the contents of the replica database 260 into the local update database 270 when the contents of the replica database 260 are updated or deleted. The master database 150 is updated by transmitting the data written here to the master site 100 by the master update request unit 120. Master update request starting unit 25
0 activates the master update request unit 220 periodically by time control such as a timer. The search unit 280 searches the replica database 260 or the local update database 270 in response to a request from the client 300, and transmits the result to the client 300. The replica database 260 is a duplicate database of the master database 150. The local update database 270
This is a database that is written when the replica database 260 is modified or deleted. This database is referenced when the master database 150 is updated, and is cleared after the update.

The client 300 is used by a database operator to search and update based on a replica database at a replica site. This client 3
00 and a client and a replica site may be executed on the same computer.

(2) Overall Flow (A) User Operation The user selects an appropriate replica site from the client 300, and retrieves the replica database and the local update database using the search unit 280. When the data in the replica database 260 is to be corrected, the data to be corrected in the replica database 260 is extracted, corrected, and stored in the local update database 270. The user repeats this process, and saves the results of the correction so far in the master database 1.
When it is desired to update the master update request to the master site 100, a master update request is transmitted to the master site 100 using the master update request unit 220. In addition, since the master database 150 may have been updated by another client 300, the user uses the replica update request unit 230 to update the replica database 270 so that the master site 1 is updated.
00 to send a replica update request.

(B) Operation of Replica Site The replica site 200 holds a replica database 260 copied from the master database of the master site 100, and a local update database 270 holding locally updated data. In response to a request from the client 300, a request is issued to the master site 100 to reflect the locally updated data in the master database 150. As a result, the replica database 260 is updated, and the local update database 270 is cleared.
Further, at the request of the client 300, a request for updating the replica database 260 without updating the master database 150 can be made to the master site 100. As a result, the replica database 260 is updated. Further, a request is periodically made to the master site 100 to reflect the data in the local update database 270 to the master database 150. As a result, the master database 150 is updated without the user instructing the master update request.

(C) Operation of Master Site In the master site 100, the master database 15 is periodically and in response to a request from the replica site 200.
The data of 0 is transmitted to the replica site 200. Further, the master database 150 is changed in response to a request from the replica site 200.

(3) Replica Update FIG. 7 is a diagram for explaining processing and communication between the replica site 200 and the master site 100 when the replica site 200 requests to update the replica database 260. First, the control unit 210 receives an update request for the replica database 260 from the client 300, and activates the replica update request unit 220. The replica update request unit 220 checks whether the local update database 270 is empty (step SR0)
7010). When the local update database 270 is not empty, a message “local update database is not empty” is transmitted to the client 300 through the control unit 210. When the local update database 270 is empty, the “replica update request” is sent to the master site 100.
(Step SR07020). When receiving the master database 150 from the master site 100, the master database 150 is replaced with the replica database 260 (step SR07030).

At master site 100, control unit 110 receives the replica update request, and replica update unit 130
Start Replica updating section 130 checks whether or not requests (master update request and replica update request) from another replica site have been received (step SM07010). When processing another request,
Send "Master database is busy" to the requesting replica site. If there is no other request, the master database 150 is transmitted to the requesting replica site 200 through the control unit 110 (step SM07020).

(4) Search Update at Master Site The master database 150 can be searched directly or updated at the request of the client 300. This control is performed by exclusive control. When updating the master database, the master database is updated as a normal version without a site ID. The version number is a number obtained by adding 1 to the latest registered version number. Here, the version with the site ID in the master database 150 can be searched but cannot be changed.

(5) Local Update Database The update of the replica database 260 at the replica site is performed based on the contents of the replica database 260, and the update result is stored in the local update database 270. The updated version information at this time is a version with a site obtained by adding 1 to the version number of the data to be updated and adding the site ID of the replica site. Here the replica database 26
The data of the version with the site ID in 0 cannot be changed.

(6) Master Update FIG. 8 shows the processing between the replica site 200 and the master site 100 when a request is made to update the master database with data in the locally updated local update database 270. It is a figure explaining communication. There are the following three methods for activating the master update request unit 220 at the replica site 200. -When the client 300 instructs to start-When a start request is periodically issued from the master site 100-When the replica site 200 itself periodically issues a start request Master update request started by any of these Part 22
0 transmits a master update request to the master site 100 together with the contents of the local update database 270 (step SR08010). When receiving the updated contents of the master database from the master site 100, the replica site 200 replaces the existing replica database 260 with the existing replica database 260 (step SR08020). The local update database 270 is cleared (step SR08030).

The master site 100 receives the master update request from the control unit 110 and
Start Master updating section 120 checks whether or not requests (master update request and replica update request) from other replica sites have been received (step SM08010). When processing another request,
Send "Master database is busy" to the requesting replica site. If there is no other request, the conflict determination unit 125 is activated, and the conflict information is checked by comparing the version information existing in the master database 150 with the version information of the transmitted local update database (step SM08020). As a result of the conflict determination, when it is determined that the version is the normal version, the transmitted data of the local update database is registered in the master database 150 as the normal version (after deleting the site ID of the transmitted version information) (step). SM08030).

As a result of the conflict determination, when it is determined that the version is the version with the site ID, the transmitted data of the local update database is registered in the master database 150 as the version with the site ID (as transmitted) (step SM08040). . Replica site 200 requesting updated master database 150
(Step SM080)
50).

FIG. 9 is a diagram showing a processing flow when comparing the version information of the master database 150 with the version information of the local update database to check whether or not there is a conflict. Master database 150
Extract the latest version information of The version number is Mver (step S09010). Extract the version information of the local update database sent. The version number is set to Over (step S09020). It is determined whether Mver + 1 is equal to Uver (step S09030). This comparison checks whether the received local update database data is the latest update data for the master database.

If the results are equal, there is no conflict, and the result is registered as "normal version" (step S09040). When the results are not equal, Mv
It is determined whether er + 1 is greater than Uver (step S09050). If it is larger, it is registered as "version with site ID" (step S090)
60). Otherwise, it is transmitted to the requesting replica site 200 as a version error.

(7) Activation of Timer from Master Site The control unit 110 of the master site 100 periodically activates the master update request activation request unit 140 by setting a timer or the like. The master update request activation request unit 140 transmits an instruction to send a master update request to all replica sites 200. Control unit 21 of replica site 200
0, upon receiving this request, the master update request unit 220
Is started, a master update request is sent together with the contents of the local update database 270, and finally, the master database is updated, a copy to the replica database is created, and the local update database is cleared.

(8) Start of Timer from Replica Site The control unit 210 of the replica site 200 periodically starts the master update request starting unit 250 by setting a timer or the like. The master update request activating unit 250 activates the master update requesting unit 220 and activates the local update database 27.
A master update request is sent with the contents of 0, and finally,
Update the master database, create a replica on the replica database, and clear the local update database.

Second Embodiment (Algorithm 2) (1) Description of Configuration Diagram FIG. 10 is a diagram for explaining a functional configuration of a second embodiment of the present invention.

The master site 100 includes a control unit 110,
Master update unit 120, replica update unit 130, checkout unit 160, unlock unit 170, search update unit 1
80 and a master database 150. The control unit 110 controls each function (the master update unit 120,
It controls the replica update unit 130, the checkout unit 160, the unlock unit 170, the search update unit 180), and controls the transmission and reception of data through the network. The checkout unit 160 acquires the right to change the data requested from the replica site 200. During the check-out, the data updated at the replica site 200 is the normal version. Master update unit 120
Processes a data update request of the master database 150 from the replica site 200. When updating the master database 150, a conflict determination unit 125 for determining a conflict state is provided. The unlock unit 170 relinquishes the right to update the data specified by the replica site 200.

The replica update unit 130 processes a transfer request of the master database 150 from the replica site 200. The search and update unit 180 searches and updates data by exclusive control. The data search of the master database 150 is performed in response to a request from the client 300, and the result is returned. When updating the search result, the master database 150 is updated as a normal version.
The master database 150 is the only database existing in the network, and its data is copied to the replica database at each replica site, and the replica database is searched and updated.

The replica site 200 includes a control unit 210,
Master update request unit 220, replica update request unit 23
0, local update unit 240, checkout request unit 29
0, a check-in request unit 295, a search unit 280, a replica database 260, and a local update database 270. The control unit 210 controls each function (the master update request unit 220, the replica update request unit 230,
Local update unit 240, checkout request unit 290,
It controls the check-in request unit 295 and the search unit 280) and controls the transmission and reception of data through the network.
The checkout request unit 290 transmits a checkout request to the master site 100 in order to acquire a right to update data to be updated in the local update database 270 according to an instruction from the client 300. The check-in request unit 295 activates the master update request unit 220 when the check-out request is successful, transmits an unlock request to the master site 100 after the end, and relinquishes the right to update the data.

The master update requesting unit 220 transmits the data to be updated in the local update database 270 to the master site 100, requests to update the master database 150, receives the updated master database 150, and 260 is replaced and the local update database 270 is cleared. The replica update requesting unit 230 operates when the local update database 270 is empty, requests to transmit the contents of the master database 150 of the master site 100, and replaces the replica database 260 with the received contents of the master database. The local update unit 240 writes the contents of the replica database 260 to the local update database 270 when the contents of the replica database 260 are updated or deleted. The master database 150 is updated by transmitting the data written here to the master site 100 by the master update request unit 120. The search unit 280 searches the replica database 260 or the local update database 270 in response to a request from the client 300, and transmits the result to the client 300. The replica database 260 is a duplicate database of the master database 150. The local update database 270 is a replica database 2
This is a database written when 60 is modified or deleted. This database is referenced when the master database 150 is updated, and is cleared after the update.

The client 300 is used by the database operator to search and update based on the replica database at the replica site. This client 3
00 and a client and a replica site may be executed on the same computer.

(2) Outline of Overall Flow (A) User Operation The user selects an appropriate replica site from the client 300 and retrieves the replica database and the local update database using the search unit 280. When the data in the replica database 260 is to be corrected, the data to be corrected in the replica database 260 is extracted, corrected, and stored in the local update database 270. The user repeats this process, and saves the results of the correction so far in the master database 1.
When it is desired to update the master site 100, the master site 100 is requested to update the master using the checkout request unit 290. In addition, since the master database 150 may have been updated by another client 300, the user uses the replica update request unit 230 to update the replica database 270 so that the master site 1 is updated.
00, a replica update request can also be sent.

(B) Operation of Replica Site The replica site 200 holds a replica database 260 copied from the master database of the master site 100, and a local update database 270 holding locally updated data. In response to a request from the client 300, a request is issued to the master site 100 to reflect the locally updated data in the master database 150. As a result, the replica database 260 is updated, and the local update database 270 is cleared.
Further, at the request of the client 300, a request for updating the replica database 260 without updating the master database 150 can be made to the master site 100.

As a result, the replica database 260 is updated. Further, a request is periodically made to the master site 100 to reflect the data in the local update database 270 to the master database 150. As a result, the master database 150 is updated without the user instructing the master update request.

(C) Operation of Master Site In the master site 100, the master database 15 is periodically and in response to a request from the replica site 200.
The data of 0 is transmitted to the replica site 200. Further, the master database 150 is changed in response to a request from the replica site 200.

(3) Master Update Of the components of the second embodiment, those having the same functions as those of the first embodiment are not described. FIG. 11 shows a process between the replica site 200 and the master site 100 when the master database is updated with the locally updated data in the local update database 270 when a check-out request for obtaining an update right is issued. It is a figure explaining communication with. Replica site 200
The checkout requesting unit 290 started in step (1) transmits a checkout request to the master site 100 together with data to be updated in the local update database 270 (step SR11010). When the replica site 200 receives a successful check-out from the master site 100, it activates the check-in request unit 295 to update the master database 150.

The master site 100 receives the check-out request from the control unit 110,
Start 20. Check-out unit 160 checks whether a check-out request has been received from another replica site (step SM11010). When a check-out request is received from another party, the master database is "busy" to the requesting replica site.
Send that. If no other request has been received, it is checked whether the requested data exists in the master database 150 (step SM11020). When there is no data to be updated, “Not Found” is transmitted to the requesting replica site.

If there is data to be updated, it is checked whether the data has been checked out. (Step SM1
1030). Step SM if checked out
Branch to 11050. If not, the checkout flag 23 of the data is set to true,
Register the site ID 24 as the site ID of the replica site that requested the check-out (step SM1104)
0). The success of the check-out is transmitted to the requesting replica site (SM11050). The replica site receives this and activates the check-in request unit 295.

FIG. 12 is a diagram for explaining processing and communication at the replica site and the master site in response to a check-in request. In the replica site 200, when the control unit 210 receives from the master site that the check-out is successful, the control unit 210 activates the check-in request unit 295.

The check request unit 295 activates the master update request unit 220 to transmit data to be updated in the local update database to the master site, updates the master database 150 and the replica database 260, and clears the local update database 270. (Step SR12010). The operation of the master update requesting unit 220 is the same as that of the first embodiment except for the conflict determination unit 125, and a description thereof will be omitted. When the update is completed, an unlock request is transmitted to master site 100 (step SR1202)
0).

The master site 100 receives the unlock request from the control unit 110 and activates the unlock unit 170. The unlock unit 170 determines that the checkout flag of the data in the master database 150 requesting the unlock is true, and that the site ID 2
4 and the site ID of the replica site that made the unlock request
Is checked (step SM12030).
If they do not match, an "unlock error" is sent to the requesting replica site. If they match,
The checkout flag 23 for the data in the master database 150 is set to false, the site ID 24 is cleared, and the unlock success is transmitted to the requesting replica site.

The entire operation of the master updating section 120 is the first
This embodiment is the same as that of the first embodiment, but only the conflict determination unit 125 is different. FIG. 13 is a diagram showing a flow of processing when comparing the version information of the master database 150 with the version information of the local update database to check whether or not there is a conflict. It is checked whether the check-out flag 23 of the data requested to be updated is true and has the same site ID 24 as the requesting site ID (step S13010). If that data is checked out on another site,
Judge as “version with site ID” (step S1
3020). According to this determination, the data requested to be updated is converted into a version with a site in the master database 15.
0 is registered.

In step S13010, the same site ID
, The latest version information of the master database 150 is extracted. The version number is Mver (step S1303).
0). Extract the version information of the local update database sent. The version number of these is Uve
r (step S13040). Mver + 1 and U
and ver is equal (step S1305)
0). This comparison checks whether the received local update database data is the latest update data for the master database. If the results are equal, there is no conflict, and the result is registered as "normal version" (step S13060). If the results are not equal, it is determined whether Mver + 1 is greater than Uver (step S13070). If it is larger, it is registered as "version with site ID" (step S13080). Otherwise,
Requesting replica site 200 as version error
Send to

Further, a configuration in which a request for updating the master database 150 is periodically made from the master site 100 to the replica site 200 or a configuration in which a request for updating the master database 150 is made periodically from the replica site 200 may be made. it can.

Third Embodiment Although the update of the master database and the update of the replica database in the second embodiment have been performed on all the respective data, this embodiment assumes that the update operation is performed only with the updated data. I do. This reduces the amount of data transferred and allows the system to operate more efficiently.

Hereinafter, differences from the second embodiment will be described. -Local update database When the data in the replica database 260 is modified,
Only the relevant data is stored in the local update database 270. Check-in request section After the check-out is completed, the master update request section 12
0 transmits only data existing in the local update database 270 to the master site 100. The master update unit updates the master database 150 with respect to the data sent from the replica site 200, transmits only the updated data to the replica site, and sets the replica site 2
00 is also copied only for the transmitted partial data of the master database.

Fourth Embodiment In the first to third embodiments, the local update database 270 can be searched, but is not considered as an update target. In this embodiment, the local update database 270 can be updated based on the first embodiment. The same can be applied to other embodiments.

Hereinafter, only the differences will be described. (1) Update at Replica Site FIG. 14 is a diagram illustrating the flow of processing when registering data in the local update database 270 at the replica site 200. It is checked whether the data to be registered is an updated replica database (step S140)
10). If so, the current version number of the replica database 260 is extracted (verified) (step S14020). Local update database 27
When registering data in 0, the latest version number of the local update database 270 is extracted (step S14030). A new version is created by adding 1 to the extracted version number (Ver) (step S14040). The new version number and the site ID of the replica site 200 are used as version information, and data is registered in the local update database 270.

(2) Master Update The process of the master update request is the same as that of the first embodiment, but the contention determination section 1 determines which version (site or normal?) Is to be registered in the master database.
25 are different, and will be described with reference to FIG. Extract the oldest version number of the transmitted update data of the local update database (referred to as Over1)
(Step S15010). The latest version of the transmitted update data of the local update database is taken out (referred to as Over2) (step S15020).
The current version number of the master database is extracted (Mver) (step S15030). Mv
er + 1 is compared with Over1 (step S150)
40). If the results are equal, it is determined that the version is the normal version (step S15050). If the results are not equal, Mver + 1 is compared with Over2 (step S15060). As a result, when Mver + 1 is large, it is determined that the version has the site ID (step S1).
5070). Otherwise, an error occurs.

All data relating to the data sent from the local update database in the version determined in this way are registered in the master database.

Fifth Example (Example as a Program) Further, the present invention is not limited to only the above embodiment. For example, in the data update control system shown in FIGS. 6 and 10, each function of each means constituting the master site and the replica site is programmed, and the
-Write the data on a recording medium such as a ROM
By mounting the OM on a computer equipped with a CD-ROM drive at each site and loading the program into the computer, it is possible to realize functions similar to those of the above-described embodiment.

As a recording medium, a semiconductor medium (eg, ROM, IC memory card, etc.), an optical medium (eg,
Any of DVD-ROM, MO, MD, CD-R, etc.) and magnetic media (for example, magnetic tape, flexible disk, etc.) may be used.

The program for realizing the functions of the present invention may be provided not only in the form of a medium but also by communication or broadcast waves.

[0083]

As described above, according to the present invention, data consistency is maintained when the same version of the database is not changed at the same time. Even if the same version of the database is changed at the same time, the data of the site that requested the update of the master database first becomes the normal version, but the data of the site that requested the update later is the site ID. Will be registered in the master database as a version marked with, the data for which an update request has been made later will not be lost, and the user can refer to and update the data at any time.

Further, since the normal communication between the master site and the replica site is only regular update of the replica and update of the master database from the replica site, the communication load on the network can be reduced. Furthermore, by transmitting only the data to be updated when transmitting the data transmitted in the update request and the update result, the total rewriting of the database can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an operating environment of a data update control system according to the present invention.

FIG. 2 is a diagram showing a computer hardware configuration of a master site, a replica site, and a client on which the present invention operates.

FIG. 3 is a diagram showing a data structure of three databases used in the present invention.

FIG. 4 is a diagram showing a transition of version information when data of a master database not including an update of a local update database itself of the present invention is updated.

FIG. 5 is a diagram showing a transition of version information when updating data in a master database including updating of a local update database according to the present invention.

FIG. 6 is a diagram for explaining a functional configuration of the first embodiment.

FIG. 7 is a diagram illustrating processing and communication when an update request is made to the replica database according to the first embodiment;

FIG. 8 is a diagram illustrating processing and communication at the time of a master update request according to the first embodiment.

FIG. 9 is a diagram illustrating a flow of processing of a conflict determination unit according to the first embodiment.

FIG. 10 is a diagram illustrating a functional configuration of a second embodiment.

FIG. 11 is a diagram illustrating processing and communication for a checkout request according to the second embodiment.

FIG. 12 is a diagram illustrating processing and communication for a check-in request according to the second embodiment.

FIG. 13 is a diagram illustrating a flow of a process performed by a conflict determination unit according to the third embodiment.

FIG. 14 is a diagram illustrating a flow of processing when registering data in a local update database according to the fourth embodiment.

FIG. 15 is a diagram illustrating a flow of a process performed by a conflict determination unit according to the fourth embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input means, 2 ... Output means, 3 ... CPU, 4 ... Memory, 5 ... Storage means, 6 ... Medium drive device, 7 ... Network interface, 10 ... Control part, 21 ... Version information (version number), 22 ... Version information (site ID), 23 ... checkout information (checkout flag), 24 ... checkout information (site ID),
25: data, 100: master site, 120: master update unit, conflict determination unit, 130: replica update unit,
140: master update request start request unit, 150: master database, 160: checkout unit, 170:
Unlock unit, 180 search / update unit, 200 replica site, 210 control unit, 220 master update request unit, 230 replica update request unit, 240 local update unit, 250 master update start request unit, 260 Replica database 270 local update database 280 search unit 290 checkout request unit
295: check request unit, 300: client, 40
0 ... Local Area Network (LA
N).

Claims (14)

[Claims] 1. A distributed data management system in which one master site holding a master database and one or more replica sites holding a replica database that is a copy of the master database are connected via a network, wherein the replica site A local update database that holds the updated data of the replica database, a request to reflect the updated data to the master database, and the contents of the updated master database are received and the replica is replicated. A master update request unit that creates a database, the master site includes a master update unit that receives a request from the master update request unit and updates a master database, and the master update request unit of the replica site includes: , That Requesting the master site to update the content of the local update database at the replica site of the master site, and at the master site, the master update unit receives the update request, updates the master database, and updates the master database. A data update control system wherein a replica database is updated by transmitting an updated master database to a master update request section of a replica site that has requested an update when updating is successful. 2. The data update control system according to claim 1, wherein said master database comprises:
The data update control system, wherein the replica database and the local update database also hold version management information that compares a version number with site identification information of a replica site. 3. The data update control system according to claim 2, wherein a data of a normal version database which does not hold the site identification information of the version management information and a site version having the site identification information are provided. Update control system. 4. The data update control system according to claim 3, wherein a local update unit is provided at the replica site, and when the local update unit updates data of a normal version of the replica database, a result of the update is used. A data update control system, wherein the data is stored in the local update database, and the stored version registers a newer version than the replica version and the ID of the replica site as site identification information. 5. The data update control system according to claim 4, wherein when the local update unit of the replica site updates the data of the local update database, the result is stored in the local update database. A data update control system wherein the stored version registers a newer version number than the original version of the updated local update database and the ID of the replica site as site identification information. 6. The data update control system according to claim 3, wherein a conflict determination unit is provided in a master update unit of the master site, and the conflict determination unit determines that a latest version of a master database of the master site is in the replica site. If it is smaller than the oldest version of each data of the local update database, it is determined to be a normal version, otherwise it is determined to be a site-attached version, and when the conflict determination unit determines that it is a normal version, the master update unit Register all the contents of the local update database to the master database as a normal version, and if the determination is a version with a site, register the contents of the local update database to the master database as a version with a site;
The updated master database is transferred to a replica site where a master update has been requested, and the master update request unit copies the master update request to the replica database and clears the local update database. Data update control system. 7. The data update control system according to claim 1, wherein the master update request unit of the replica site sends only data to be updated to the master site and performs a partial update of the master database. A data update control system. 8. The data update control system according to claim 1, further comprising a replica update request unit provided at said replica site, wherein said replica update request unit is provided when said local update database is empty. Requesting the master site to transfer the contents of the master database to the master site, and copying the master database to the replica database at the replica site. 9. The data update control system according to claim 1, wherein the master site is configured not to receive requests from two or more replica sites at the same time. 10. The data update control system according to claim 1, wherein the master site periodically updates the master database and the replica database by requesting a replica site to periodically operate a master update request unit. A data update control system, characterized in that: 11. The data update control system according to claim 1, wherein the replica site periodically updates a master database and a replica database by periodically operating a master update request unit. Data update control system. 12. In a distributed data management system in which one master site holding a master database and one or more replica sites holding a replica database, which is a copy of the master database, are connected via a network, the replica site A local update database that holds the updated data of the replica database, a checkout request unit that requests the right to exclusively change the master database of the master site, and sends the updated data to the master database. A master update request unit that requests to reflect, receives the contents of the master database of the update result, and creates a replica database that is a replica,
A check-in requesting unit for requesting to abandon the exclusive right of the master database after updating the master database, wherein the master site has a right to monopolize and change the master database in response to a check-out request from the replica site. A check-out unit for setting inspection, a master update unit for receiving a request from the master update request unit and updating a master database, and an unlock for executing a request for relinquishing the exclusive right of the master database from the replica site. The replica site sends a request to the master site by specifying the data to be checked out by the checkout request unit, and when the master update request unit succeeds in the checkout, Data to master site Receiving the update result and updating the replica database, and when the check-in request unit succeeds in updating the replica database, sends a request for waiver of the exclusive right to the master site, clears the local update database, and clears the master The site checks out the data to be checked out received by the checkout unit from the replica site, sends the result to the requesting replica site, and transmits the data of the local update database sent by the master update unit. Updating the master database and sending the updated master database to the requesting replica site, and canceling the check-out when the unlocking unit receives a request for waiver of the exclusive right from the replica site. Update control system 13. A distributed data management system in which one master site holding a master database and one or more replica sites holding a replica database, which is a copy of the master database, are connected via a network. A local update database that holds the updated data of the replica database, a request to reflect the updated data to the master database, and the contents of the updated master database are received and the replica is replicated. A master update request unit that creates a database, the master site includes a master update unit that receives a request from the master update request unit and updates a master database, and the master update request unit of the replica site includes: , Requesting the master site to update the contents of the local update database at the replica site to the master site, wherein at the master site, the master update unit receives the update request;
Updating the master database, and updating the replica database by transmitting the updated master database to the master update request unit of the replica site that has issued the update request when the update is successful. Data update control method. 14. A distributed data management system in which one master site holding a master database and one or more replica sites holding a replica database that is a copy of the master database are connected via a network, wherein the replica site A local update database that holds the updated data of the replica database, a request to reflect the updated data to the master database, and the contents of the updated master database are received and the replica is replicated. A master update request unit that creates a database, the master site includes a master update unit that receives a request from the master update request unit and updates a master database, and the master update request unit of the replica site includes: , Requesting the master site to update the contents of the local update database at the replica site to the master site, wherein at the master site, the master update unit receives the update request;
A program for updating the master database and updating the replica database by transmitting the updated master database to the master update request section of the replica site that requested the update when the update was successful was recorded. Computer readable recording medium.