JPH0619768A - Duplicate data update system - Google Patents

Abstract

PURPOSE:To provide a duplicate data update system by which a processing for ensuring the consistency of data on all duplicate data is considerably simplified and by which the complication of the processing does not depend on the number of data bases and duplicate data by updating original data at the time of updating duplicate data in the distributed data base. CONSTITUTION:When an update request is that from a user in a step 103, original data information is retrieved in a step 105. When it exists, an original data update request is issued in a step 106. When it does not exist, the update processing of self data is executed in a step 107. An extraction data update request is issued to an extraction destination based on data extraction destination information in a step 110. When the update request is not from the user in the step 103, a processing from the step 107 to the step 110 is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplicate data updating method, and more particularly to a duplicate data updating method between distributed databases in which a plurality of computer systems are connected by communication lines or buses.

[0002]

2. Description of the Related Art In order to efficiently use a large-scale database in a wide area, the number of nodes and the number of duplicate data constituting the distributed database increase. Also, the number of database users will increase as the database becomes larger. Therefore, the likelihood of performing duplicate data updates in many database systems also increases.

In the conventional duplicated data update method, when an update request is issued for data existing in a local database in a distributed database, first, the data to be updated is requested in the local database that made the update request. After the update, the same data as the update target data, that is, a duplicate data update request of another local database in which the duplicate data exists is issued and the duplicate data is updated in the distributed database.

[0004]

SUMMARY OF THE INVENTION In the above-mentioned conventional duplicated data update method, since the data to be updated is first updated in the database which is requested to be updated, the duplicated data in the other databases are updated. If an update request is issued for the same data in multiple databases at the same time, that is, duplicate data, the updated data may be in different states, which update process should be enabled or disabled. There is a problem that it is difficult to maintain the consistency of the entire duplicate data by rolling back the update process.

An object of the present invention is to provide a duplicated data updating method capable of significantly reducing the processing for maintaining the consistency of duplicated data.

[0006]

According to a first aspect of the present invention, there is provided a duplicated data updating method for updating duplicated data existing between computer systems constituting a distributed database, wherein the duplicated data is updated when the duplicated data is updated. The feature is that priority is given to the update of the data that is the origin of the data.

Further, in the duplicated data update method of the second invention, the data extraction destination information which is information on the extraction destination database which is provided by extracting the duplicated data in advance when the duplicated data is generated between a plurality of databases is provided. It is registered in the extraction source database of the duplicated data, and the origin data information, which is information about the database of the origin data that is the origin of the duplicated data, is registered in the extraction destination database, and the update request for the duplicated data is sent from the user. A first step of determining whether the request is a request, a second step of searching the origin data information when the determination of the first step is from a user, and a second step of A third step of issuing an update request for the origin data based on the origin data information when it can be retrieved; Note that when the origin data information cannot be retrieved in the second step, the data for which the update request has been made is updated, and then the data extraction destination information is examined, and based on this, an extraction data update request is issued to the data extraction destination database. And the fifth step of performing the fourth step when not requested by the user in the first step.

[0008]

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

FIG. 2 is a schematic diagram of a distributed data system that implements the duplicated data update method of the present invention.

The distributed data system shown in FIG. 2 has six distributed databases 201 to 206. And the data 207-2 which those databases have
All 12 are the same data, that is, duplicate data.

At the time of generating the duplicated data, the information of the database of the data extraction destination (hereinafter referred to as the data extraction destination information) is registered in the data extraction source, and together with this, it becomes the origin of the duplicated data registered in the data extraction source. The information of the existing database (hereinafter referred to as origin data information) is copied and registered in the data extraction destination.

The series of duplicate data generation is in the form of a tree structure whose root is the origin data. Each database that has duplicate data has origin data information that is the location information of the data that is the origin of the duplicate data, and data extraction destination information that is the location information of another duplicate data that is further extracted from the duplicate data. Is managing.

In FIG. 2, it is assumed that the data 208 to 212 all originate from the origin data 207. Therefore, the origin data information 21 of the databases 202 to 206
9 to 223, the database 201 in which the origin data 207 exists and the information on the origin data 207 are registered. This information is registered by copying the origin data information of the data extraction source to the data extraction destination when the duplicate data is generated. Since the database 201 is the database having the origin data 207 in FIG. 2, the origin data information is not necessary in the system of FIG.

Data extraction destination information is registered in the database from which the data has been extracted. In FIG. 2, since the data 210 and 211 are extracted from the data 208, the data extraction destination information 21 of the database 202.
4, information of databases 204 and 205 and information of data 210 and 211 are registered. Data extraction destination information 216 to 21 of the databases 204 to 206
No information is registered in the arrangement shown in FIG.

In such a state, assume that an update request is issued to the data 208. The database 202 is data 2
Before updating 08, the origin data information 219 is searched, it is confirmed that the origin data of the data 208 is the origin data 207 of the database 201, and a request for updating the origin data 207 is issued to the database 201.

In the database 201, the origin data 207
After executing the update of the data, the data extraction destination information 213 is searched, and the origin data 207 to the data 208 and the data 209 are searched.
Make sure that is extracted. Then, an update request is issued to the databases 202 and 203 in which the respective data exist.

In the databases 202 and 203, the duplicate data 208 and 209 are updated in the same manner as the update processing in the database 201. Then, the data extraction destination information is searched, and the database 20 is further updated.
A request for updating the duplicated data extracted in Nos. 4, 205 and 206 is made.

If an update request is issued to a plurality of data from the duplicated data 207 to 212 almost at the same time,
For example, consider a case where an update request for the data 212 is issued before the update processing for the data 208 reaches the data 212.

The database 206 is the origin data information 2
23 is searched and an update request for the origin data 207 of the data 212 is issued to the database 201. The database 201 attempts to update the origin data 207, but an update request from the database 202 has already been issued to the data 207, and the update request from the database 206 is rejected because this update process is in progress and the data 212 Update request is invalid.

In this way, only one update is temporarily effective in all duplicate data, and the consistency of duplicate data is guaranteed.

FIG. 1 is a flow chart showing an embodiment of the duplicated data update method of the present invention in each database.

When the update request is received, the process is started (step 101). First, the update request is analyzed (step 102), and it is determined whether the update request is issued directly from the application program of the user or from another database (step 103).

When it is determined in step 103 that the update request is directly issued by the user (YES branch of step 103), the origin data information is searched (step 104).

When the origin data information is retrieved and the origin data information is present (YES branch of step 105), the origin data is updated to the database having the origin data based on the origin data information so that the origin data is updated. A request is made (step 106) and the process is ended (step 111).

When the origin data information does not exist in the search of step 104 (NO branch of step 105), this is because the database which has received the update request from the user has the origin data. Update the origin data in the database (step 10
7) After that, the data extraction destination information is investigated (step 108), and when there is no extraction destination information (step 10).
(NO branch of 9), and the process is ended there (step 11
1) When there is extraction destination information (YE of step 109)
S branch), issues an extraction data update request to update the data in the extraction destination database based on this extraction destination information (step 110), and ends the processing (step 11).
1).

When it is determined in step 103 that the update request is issued from another database (step 10
No branch 3), this update request is an update request for the source data issued in step 106 or an update request for the extracted data issued in step 110 in the other database already described, so these updates are immediately performed. In order to perform the processing, the processing of steps 107 to 111 already described is performed.

[0027]

As described above, according to the duplicate data update method of the present invention, when an update request is issued in a distributed database environment in which a plurality of duplicate data having the same duplicate portion exists, the duplicate data is updated By updating the only existing origin data in the first, even if multiple updates occur almost at the same time, only the transactions that are allowed to update the origin data are valid, and multiple updates have the same origin data at one time. There is an effect that the consistency of the data within the duplicate data is guaranteed without being performed on the duplicate data.

Further, since there is no control node for collectively managing duplicated data and the same processing is performed by each database, it is possible to avoid processing concentration on one system as much as possible and realize load distribution. It also has an effect.

Further, even if the number of databases constituting the distributed database and the number of duplicated data in the databases increases, the processing contents are not changed and the complexity of the processing is not increased.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of a duplicate data updating method of the present invention.

FIG. 2 is a schematic diagram showing a distributed database system that implements the duplicated data update method of the present invention.

[Explanation of symbols]

 101-111 Flow chart steps 201-206 Database 207 Origin data 208-212 Data 213-218 Data extraction destination information 219-223 Origin data information

Claims (2)

[Claims] 1. In a duplicate data update method for updating duplicate data existing between computer systems constituting a distributed database, the update of the source of the duplicate data is preferentially executed when the duplicate data is updated. A duplicate data update method characterized by. 2. The data extraction destination information, which is information about the extraction destination database that is provided by extracting the duplicate data in advance when the duplicate data is generated between a plurality of databases, is registered in the extraction source database of the duplicate data, Origin data information, which is information about a database of origin data that is the origin of duplicate data, is registered in the extraction destination database, and it is determined whether or not the update request for the duplicate data is a request from a user. And a second step of retrieving the origin data information when the judgment of the first step is from the user, and a step of retrieving the origin data information in the second step. Based on the third step of issuing an update request for the origin data based on the When the data cannot be searched, the data requested for update is updated, the data extraction destination information is checked, and the extraction data update request is issued to the data extraction destination database based on the information. The fourth step and the first step are used. And a fifth step of performing the fourth step when it is not requested by a person.