System and method for database synchronization

• US 5,758,150 A
• Filed: 10/06/1995
• Issued: 05/26/1998
• Est. Priority Date: 10/06/1995
• Status: Expired due to Term

• Current Assignee: Tele-Communications, Inc. (Comcast Corporation)
• Original Assignee: Tele-Communications, Inc. (Comcast Corporation)
• Inventors: Lee, Michelle Lee, Bell, Dennis Leroy, Hagen, Richard Lee, Cozzolino, David Lawrence
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): ROBINSON, GRETA LEE
• Application Number:
  US08/539,957
• Time in Patent Office: 963 Days
• Field of Search: 395/610, 395/618, 395/616, 364/222.81
• US Class Current: 1/1
• CPC Class Codes: G06F 16/27 Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor
• CPC Class Codes: G06F 16/275 Synchronous replication
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A database synchronization system (10) is disclosed that synchronizes the content of a central database stored on a central computer (16) with one or more remote databases stored on one or more remote computers (18). A data extract and transfer application (20) is provided on each of the remote computers (18). A migrator application (26) processes the audit trail files (24) of the remote computer (18) to create a database of change (28). When the database of change (28) reaches a size threshold, the data extract and transfer application (20) shuts down the migrator application(26), processes the database of change (28), and restarts the migrator application (26) to begin the creation of another database of change. The data and information in the database of change are converted into a series of flat files (48) that are transferred over a communications line (14) from each of the remote computers (18) to the central computer (16).

Claims

1. A database synchronization system, comprising:

a central computer storing a central database;

at least one remote computer remote from the central computer and having at least one associated database;

a communications link coupling the central computer to the remote computer; and

a data extract and transfer application stored on the remote computer, including a plurality of audit trail files for storing changes to the associated database, a migrator application capable of processing the audit trail files to extract the changes thereto and convert the changes into a first database of change, a table move module capable of executing a database command to rename the first database of change to allow the migrator application to create a second database of change, a flat file module capable of converting the first database of change into flat files suitable for transfer to the central database, and a file transfer module capable of transferring the flat files to the central computer over the communications link.

2. The database synchronization system of claim 1, further comprising means stored on the remote computer for opening the audit trail files during processing of the audit trail files by the migrator application.

3. The database synchronization system of claim 1, further comprising means stored on the remote computer for dropping the first database of change.

4. The database synchronization system of claim 1, further comprising,

means stored on the remote computer for opening the audit trail files during processing of the audit trail files by the migrator application;

and

means stored on the remote computer for dropping the first database of change.

5. A method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer, comprising the steps of:

processing the audit trail files stored on the remote computer to create a first database of change stored on the remote computer;

stopping the processing of the audit trail files when the database of change reaches a size threshold;

processing the contents of the first database of change into a format suitable for transfer to the central database stored on the central computer;

restarting the processing of the audit trail files to create a second database of change stored on the remote computer; and

transferring the processed contents of the first database of change to the central database stored on the central computer.

6. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 5, wherein the step of stopping the processing of the audit trail files when the database of change reaches a size threshold comprises the step of stopping the processing of the audit trail files when the Image Table of the database of change reaches a size threshold.

7. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 5, wherein the step of stopping the processing of the audit trail files when the Image Table of the database of change reaches a size threshold comprises the step of stopping the processing of the audit trail files when the Image Table reaches a size threshold of between approximately eight and approximately twenty megabytes.

8. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 5,

wherein the step of processing the contents of the first database of change comprises the step of building flat files from the data stored on the first database of change;

and

wherein the step of transferring the processed contents of the first database of change to the central database stored on the central computer comprises the step of transferring the flat files to the central database stored on the central computer.

9. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 8, further comprising the step of dropping the first database of change.

10. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 8, wherein the step of building flat files from the data stored on the first database of change further comprises the steps of,

selecting a processor and an associated data storage device on the remote computer for building one or more flat files;

determining whether the processor is operational;

selecting the data from the first database of change; and

building flat files if the processor is determined to be operational.

11. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 8, wherein the step of building flat files from the data stored on the first database of change further comprises the steps of,

selecting a first processor of several available processors and an associated data storage device on the remote computer for building one or more flat files;

determining whether the first processor is operational;

selecting among the several available substitute processors if it is determined that the first processor is nonoperational and repeating the selection until an operational processor is found;

selecting the data from the first database of change;

building flat files on the selected processor.

12. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 8, wherein the step of building flat files from the data stored on the first database of change further comprises the steps of,

selecting a processor and an associated data storage device for building one or more flat files;

determining whether the data storage device has available space;

selecting the data from the first database of change; and

building flat files if the data storage device is determined to have available space.

13. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 8, wherein the data storage device is a disk drive.

14. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 8, wherein the data storage device is a tape drive storage device.

15. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 8, wherein the data storage device is an optical disk storage device.

16. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 8, wherein the step of building flat files from the data stored on the first database of change further comprises the steps of,

selecting a processor and an associated data storage device for building one or more flat files;

determining whether the data storage device has available space;

determining whether the processor is operational;

selecting the data from the first database of change; and

building flat files if the data storage device is determined to have available space and the processor is determined to be operational.

17. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 5,

wherein the step of processing the contents of the first database of change comprises the step of building flat files from the data stored on the first database of change;

and

wherein the step of transferring the processed contents of the first database of change to the central database stored on the central computer comprises the steps of,

determining whether the communications line between the central computer and the remote computer is operational; and

transferring the flat files from the remote computer to the central database stored on the central computer across the communications line when the communications line becomes operational.

18. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 17, further comprising the step of dropping the first database of change.

19. A method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer, comprising the steps of:

processing the audit trail files stored on the remote computer to create a first database of change stored on the remote computer;

stopping the processing of the audit trail files when the database of change reaches a size threshold;

restarting the processing of the audit trail files to create a second database of change in the remote computer;

selecting a CPU and an associated disk drive for building one or more flat files;

determining whether the CPU is operational;

determining whether the disk drive has available space;

selecting the data from the first database of change;

building a plurality of flat files if the CPU is determined to be operational and the disk drive is determined to have available space; and

transferring the flat files to the central computer.

20. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 19, further comprising the step of dropping the first database of change after successful receipt of the plurality of flat files by the central computer.

21. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 19, wherein the step of stopping the processing of the audit trail files when the database of change reaches a size threshold comprises the step of stopping the processing of the audit trail files when the Image Table of the database of change reaches a size threshold.

22. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 19, wherein the step of stopping the processing of the audit trail files when the Image Table of the database of change reaches a size threshold comprises the step of stopping the processing of the audit trail files when the Image Table reaches a size threshold of between approximately eight and approximately twenty megabytes.

23. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 19, further comprising the step of dropping the first database of change after successful receipt of the plurality of flat files by the central computer.

24. The method for synchronizing the content of a central database stored on a central computer with the content of a remote database stored on a remote computer of claim 19, wherein the step of transferring the flat files to the central computer comprises the steps of,

determining whether the data line between the central computer and the remote computer is operational;

and

transferring the flat files from the remote computer to the central database stored on the central computer across the data line when the data line becomes operational.