Method, system, and program product for sequential coordination of external database application events with asynchronous internal database events

• US 7,979,546 B2
• Filed: 04/15/2008
• Issued: 07/12/2011
• Est. Priority Date: 05/09/2002
• Status: Expired due to Fees

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Lindsay, Bruce G., Hamel, Elizabeth B.
• Primary Examiner(s): JEAN GILLES, JUDE
• Application Number:
  US12/103,548
• Publication Number:
  US 20080195673A1
• Time in Patent Office: 1,183 Days
• Field of Search: 709/225, 709200-204, 709/235, 709/245, 709/224
• US Class Current: 709/225
• CPC Class Codes: G06F 16/273 Asynchronous replication or reconciliation

Abstract

Database management systems, methods, 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 method of managing a database management system that includes a replication system and that has at least one database table that is subject to replication, a recovery log, and a replication signal table, said method comprising computer executable program code stored on a memory and executed on a processor to perform:

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;

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;

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

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 in the replication signal table, according to the total order of the recovery log.

2. The method of claim 1 wherein the replication command comprises a first command comprising a signal stopping the replication of changes related to the at least one database table.

3. The method of claim 1 wherein the replication command comprises a second command, and wherein the second command is a signal starting replication of changes to a database table.

4. The method of claim 3 wherein the database management system comprises at least two database tables, and the second command is a signal starting application of changes of contents of the first database table into a second database table.

5. The method of claim 1, further comprising ordering database update events in sequence using the recovery log, by using the recovery log to place asynchronous database update events in sequence between adjacent synchronous events.

6. The method of claim 1 comprising changing the schema or metadata of the at least one database table between the first command and the second command, and thereafter executing the second command.

7. The method of claim 1 comprising executing said replication command entered in the replication signal table only after taking actions in response to all preceding entries of the recovery log.

8. A database management system that includes a replication system, the database management system comprising:

a memory storing computer executable program code;

a processor executing the computer executable program code, the computer executable program code comprising;

at least one database table that is subject to the replication system;

a recovery log; and

a replication signal table;

said replication system 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;

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.

9. The database management system of claim 8 wherein the replication command comprises a first command comprising a signal stopping the replication of changes related to the at least one database table.

10. The database management system of claim 8 wherein the replication command comprises a second command, and wherein the second command is a signal starting replication of changes to a database table.

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

12. The database management system of claim 8 wherein the replication command comprises a first command comprising 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.

13. The database management system of claim 12, 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.

14. The database management system of claim 8 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.

15. A computer program product comprising a processor usable storage medium storing computer program codes and executed by the 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 at least one row in the replication signal table; and

a program code for taking replication action responsive to the recovery log entries that are positioned subsequent to the recovery log entry that pertains to the at least one row in the replication signal table, according to the total order of the recovery log.

16. The program product of claim 15 wherein the replication command comprises a first command comprising a signal stopping the replication of changes related to the at least one database table.

17. The program product of claim 15 wherein the replication command comprises a second command, and wherein the second command is a signal starting copying into the at least one database table.

18. The program product of claim 17 wherein the replication command comprises a first command comprising 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.

19. The program product of claim 15 wherein the database management system comprising take the action of said replication command entered in the replication signal table only after taking actions in response to all preceding entries of the recovery log.

20. The program product of claim 15 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.