SYSTEM AND PROGRAM PRODUCT FOR SEQUENTIAL COORDINATION OF EXTERNAL DATABASE APPLICATION EVENTS WITH ASYNCHRONOUS INTERNAL DATABASE EVENTS

• US 20080195672A1
• Filed: 04/15/2008
• Published: 08/14/2008
• Est. Priority Date: 05/09/2002
• Status: Active Grant

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Lindsay, Bruce G., Hamel, Elizabeth B.
• Granted Patent: US 7,953,707 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/273 Asynchronous replication or reconciliation

Abstract

Database management systems and program products that exploit time dependent sequential database management system processes to ensure presentation of the same data or view to one or a plurality of users through sequencing asynchronous database management operations such as recovery and replication. Sequencing is accomplished through the use of entries in sequential logs, including transaction logs, recovery logs, and other data recovery tools and applications. Uses include managing data migration and data replication.

Claims

1. A database management system that includes a replication system, a processor, and a memory, the database management system comprising:

at least one database table that is subject to replication;

a recovery log; and

a replication signal table;

said replication system creates entries in the recovery log in response to changes to a state of any one or more of the at least one database table and the replication signal table, wherein said replication signal table is a specific table that is configured for all users of the database management system, and wherein the entries in the recovery log are ordered according to a total order;

said replication system inserting into the replication signal table, at least one row that describes a replication command to the replication system relating to the at least one database table;

said replication system detecting a recovery log entry in the recovery log that pertains to the at least one row of the replication signal table;

said replication system taking replication actions responsive to the recovery log entries that are positioned subsequent to the recovery log entry that pertains to the at least one row of the replication signal table, according to the total order of the recovery log and executing said replication command entered in the replication signal table only after taking actions in response to all preceding entries of the recovery log; and

wherein the replication command comprises a first command comprising a signal stopping the copying of data into a database table.

2. The database management system of claim 1 wherein the replication command comprises a second command, and wherein the second command is a signal starting copying into a database table.

3. The database management system of claim 2 comprising at least two database tables, and the second command is a signal starting copying of contents of the first database table into second database table.

4. The database management system of claim 1 wherein the first command is a signal stopping copying of data into the database table, and a second command is a signal starting copying of contents of the database table into a second database table.

5. The database management system of claim 4 wherein the first command is a signal stopping copying of data into the database table, and the second command is a signal reinitializing copying of data into the database table.

6. The database management system of claim 4, wherein said database management system is configured and controlled for performing an operation on the database table between the first command and the second command, and thereafter executing the second command.

7. The database management system of claim 6, wherein said database management system is configured and controlled for changing the schema or metadata of the database table between the first command and the second command, and thereafter executing the second command.

8. The database management system of claim 1 wherein said replication command entered in said replication signal table also controls the processing of database events in a same transaction as said replication command.

9. A program product comprising executable program codes stored on a processor usable storage medium and executed by a processor, the program product for managing a database management system, comprising:

said database management system including a replication system, at least one database table that is subject to replication, a recovery log, and a replication signal table;

a program code for creating entries in the recovery log in response to changes to a state of any one or more of the at least one database table and the replication signal table, wherein said replication signal table is a specific table that is configured for all users of the database management system, and wherein the entries in the recovery log are ordered according to a total order;

a program code for detecting a recovery log entry in the recovery log that pertains to the replication signal table;

a program code for taking replication actions responsive to the recovery log entries that are positioned subsequent to the recovery log entry that pertains to the replication signal table, according to the total order of the recovery log;

a program code for inserting a replication command into the replication signal table; and

wherein the replication command comprises a first command comprising a signal stopping the copying of data into a database table and wherein said replication command entered in said replication signal table also controls the processing of database events in a same transaction as said replication command.

10. The program product of claim 9 wherein the replication command comprises a second command, and wherein the second command is a signal starting copying into the database table.

11. The program product of claim 10 wherein the system comprises at least two database tables, and the second command is a signal starting copying of contents of the first database table into second database table.

12. The program product of claim 11 wherein the first command is a signal stopping copying of data into the first database table, and the second command is a signal starting copying of contents of the first database table into the second database table.

13. The program product of claim 12 wherein the first command is a signal stopping copying of data into the first database table, and the second command is a signal reinitializing copying of data into the database table.

14. The program product of claim 12, wherein the database management system is configured and controlled for performing an operation on the first database table between the first command and the second command, and thereafter executing the second command.

15. The program product of claim 14, wherein the database management system is configured and controlled for changing the schema or metadata of the first database table between the first command and the second command, and thereafter executing the second command.

16. The program product of claim 9 wherein the database management system executes said replication command entered in the replication signal table only after taking actions in response to all preceding entries of the recovery log.

17. The program product of claim 9, further comprising ordering database events in sequence using the recovery log.

18. The program product of claim 17, wherein ordering the database events comprises placing asynchronous database events in sequence.

19. The program product of claim 18, wherein placing the asynchronous database events in sequence, comprises using the recovery log to place the asynchronous events in sequence between adjacent synchronous events.