DATA SYNCHRONIZATION METHOD, DATA SYNCHRONIZATION PROGRAM, DATABASE SERVER AND DATABASE SYSTEM

• US 20100036894A1
• Filed: 02/06/2009
• Published: 02/11/2010
• Est. Priority Date: 08/05/2008
• Status: Abandoned Application

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: HANAI, Tomohiro, SENDA, Riro, HARA, Norihiro
• Application Number:
  US12/367,052
• Publication Number:
  US 20100036894A1
• Time in Patent Office: Days
• US Class Current: N/A
• CPC Class Codes: G06F 16/275 Synchronous replication

Abstract

A data synchronization method is provided to enhance reliability and performance of the database. The data reflection method selection unit of the active server weights collected values in the resource utilization table by multiplying the collected values by assessment coefficients assigned to the individual collected values in an assessment coefficient table and sums up the weighted values to calculate an assessment value for each data reflection method, and determines the data reflection method whose assessment value is minimum. The log data transmission unit, according to the determined data reflection method, sends log data that is reflected on the active database to the standby server, which forms one of the duplicated servers making up the redundant configuration. The data reflection method identifies the content to be transmitted.

Claims

1. A data synchronization method for synchronizing data between an active database and a standby database in a database system, the database system being redundantly configured by having an active server to update data according to a command from a client and a standby server to take over processing from the active server in the event of a failure of the active server;

wherein the active server has the active database and the standby server has the standby database;

wherein the active server has, in addition to the active database, a resource utilization table, a resource utilization monitoring unit, a transaction control unit and a data reflection method selection unit; and

wherein the standby server has a log data application unit in addition to the standby database;

the method comprising the steps of;

starting, when the transaction control unit receives an operation command for specifying and updating data content, a transaction to process the received operation command and then reflecting on the active database the content specified by the received operation command;

collecting, by the resource utilization monitoring unit, at least utilization information on resources in each of the servers making up the database system or database operation information, and storing them in the resource utilization table;

weighting, by the data reflection method selection unit, collected values in the resource utilization table by multiplying the collected values by assessment coefficients assigned to the individual collected values in an assessment coefficient table, summing up the weighted values to calculate an assessment value for each data reflection method, and determining the data reflection method whose assessment value is minimum;

sending, by a log data transmission unit according to the determined data reflection method, log data that is reflected on the active database to the standby server, which forms one of the duplicated servers making up the redundant configuration; and

reflecting, by the log data application unit, when a finalize command to finalize the transaction is transmitted from the client to the active server, the received log data on the standby database,

wherein the data reflection method is defined by selecting one of log data content transmitting methods shown in (a) and (b);

(a) Transmitting data log representing a content of data to be updated in the database but not an index log representing a content of index update to the content of data, the index log being created on the standby server side instead; and

(b) Transmitting index log in addition to the data log.

2. The data synchronization method according to claim 1, wherein the data reflection method selection unit selects, based on the assessment value, either a data reflection method that takes a reception of the operation command as a trigger for the log data transmission or a data reflection method that takes a reception of the finalize command as a trigger for the log data transmission.

3. The data synchronization method according to claim 1, wherein the active server stores in memory the data to be stored in the active database and the standby server stores in memory the data to be stored in the standby database.

4. The data synchronization method according to claim 1, wherein two or more of the standby servers are provided in the database system and the log data transmission unit transmits, according to the selected data reflection method, the log data in a multicast communication to the plurality of standby servers, which form one of the duplicated servers making up the redundant configuration.

5. A data synchronization program to cause the active server and the standby server, both composed of computers, to execute the data synchronization method according to claim 1.

6. A database server device for synchronizing data between an active database and a standby database in a database system, the database system being redundantly configured by having an active server to update data according to a command from a client and a standby server to take over processing from the active server in the event of a failure of the active server;

wherein the active server has the active database and the standby server has the standby database;

wherein the active server has, in addition to the active database, a resource utilization table, a resource utilization monitoring unit, a transaction control unit and a data reflection method selection unit; and

wherein the standby server has a log data application unit in addition to the standby database,

said database server device comprising;

a constitutional element of the active server; and

a constitutional element of the standby server,

wherein the database server device switches between the active server and the standby server;

wherein the transaction control unit, when it receives an operation command for specifying and updating data content, starts a transaction to process the received operation command and then reflects on the active database the content specified by the received operation command;

wherein the resource utilization monitoring unit collects at least utilization information on resources in each of the servers making up the database system or database operation information and stores them in the resource utilization table;

wherein the data reflection method selection unit weights collected values in the resource utilization table by multiplying the collected values by assessment coefficients assigned to the individual collected values in an assessment coefficient table and sums up the weighted values to calculate an assessment value for each data reflection method, and determines the data reflection method whose assessment value is minimum;

wherein a log data transmission unit, according to the determined data reflection method, sends log data that is reflected on the active database to the standby server, which forms one of the duplicated servers making up the redundant configuration;

wherein, when a finalize command to finalize the transaction is transmitted from the client to the active server, the log data application unit reflects the received log data on the standby database;

wherein the data reflection method is defined by selecting one of log data content transmitting methods shown in (a) and (b);

(a) Transmitting data log representing a content of data to be updated in the database but not an index log representing a content of index update to the content of data, the index log being created on the standby server side instead; and

(b) Transmitting index log in addition to the data log.

7. The database server device according to claim 6, wherein the data reflection method selection unit selects, based on the assessment value, either a data reflection method that takes a reception of the operation command as a trigger for the log data transmission or a data reflection method that takes a reception of the finalize command as a trigger for the log data transmission.

8. A database system comprising:

an active server and;

a standby server,

wherein the active server and the standby server are configured to be for redundant configuration and synchronize data between an active database of the active server and a standby database of the standby server in the database system, wherein the active server updates data according to a command from a client and the standby server takes over processing from the active server in the event of a failure of the active server;

wherein the active server has, in addition to the active database, a resource utilization table, a resource utilization monitoring unit, a transaction control unit and a data reflection method selection unit;

wherein the standby server has a log data application unit in addition to the standby database;

wherein the transaction control unit, when it receives an operation command for specifying and updating data content, starts a transaction to process the received operation command and then reflects on the active database the content specified by the received operation command;

wherein the resource utilization monitoring unit collects at least utilization information on resources in each of the servers making up the database system or database operation information and stores them in the resource utilization table;

wherein the data reflection method selection unit weights collected values in the resource utilization table by multiplying the collected values by assessment coefficients assigned to the individual collected values in an assessment coefficient table and sums up the weighted values to calculate an assessment value for each data reflection method, and determines the data reflection method whose assessment value is minimum;

wherein a log data transmission unit, according to the determined data reflection method, sends log data that is reflected on the active database to the standby server, which forms one of the duplicated servers making up the redundant configuration;

wherein, when a finalize command to finalize the transaction is transmitted from the client to the active server, the log data application unit reflects the received log data on the standby database;

wherein the data reflection method is defined by selecting one of log data content transmitting methods shown in (a) and (b);

(a) Transmitting data log representing a content of data to be updated in the database but not an index log representing a content of index update to the content of data, the index log being created on the standby server side instead; and

(b) Transmitting index log in addition to the data log.

9. The database system according to claim 8, wherein the data reflection method selection unit selects, based on the assessment value, either a data reflection method that takes a reception of the operation command as a trigger for the log data transmission or a data reflection method that takes a reception of the finalize command as a trigger for the log data transmission.

10. The database system according to claim 8, wherein the active server stores in memory the data to be stored in the active database and the standby server stores in memory the data to be stored in the standby database.

11. The database system according to claim 8, wherein two or more of the standby servers are provided in the database system and the log data transmission unit transmits, according to the selected data reflection method, the log data in a multicast communication to the plurality of standby servers which form one of the duplicated servers making up the redundant configuration.