Synchronization of databases

• US 6,330,568 B1
• Filed: 11/05/1997
• Issued: 12/11/2001
• Est. Priority Date: 11/13/1996
• Status: Expired due to Term

• Current Assignee: Intellisync Corporation (Nokia Corporation)
• Original Assignee: Pumatech Inc.
• Inventors: Daley, Robert C., Boothby, David J., Marien, John R.
• Primary Examiner(s): Black, Thomas
• Assistant Examiner(s): JUNG, DAVID YIUK
• Application Number:
  US08/964,751
• Time in Patent Office: 1,497 Days
• Field of Search: 707/1-206
• US Class Current: 1/1
• CPC Class Codes: G06F 16/275 Synchronous replication
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A computer implemented method and a computer program for synchronizing a first and a second database, where data is provided for keeping track of whether the records of the first database have been added or changed since a previous synchronization. Based data reflecting whether the records of the first database have been added or changed since a previous synchronization, it is determined whether the records of the first database have been changed or added since the previous synchronization. If one of the records of the first database has not been changed or added since the previous synchronization, a synchronization with records of the second database is performed using a record representative of the one record at the time of a previous synchronization. The representative record is stored in a history file which contains records reflecting the contents of records of the databases at the time of a previous synchronization.

Claims

1. A computer implemented method of synchronizing a first and a second database, wherein the first database is resident on a first computer and is capable of providing change data reflecting whether the records of the database have been changed, added, or deleted since the previous synchronization, wherein the second database is resident on a second computer different from the first computer, and wherein a history file reflecting the contents of records of the databases at the time of a prior synchronization is used to perform the synchronization, the method comprising:

determining whether the records of the first database have been changed, added, or deleted since a previous synchronization, based on change data reflecting whether the records of the first database have been changed, added, or deleted since the previous synchronization, the change data comprising database generated data for keeping track of whether the records of the first database have been changed, added, or deleted since a previous synchronization;

transferring from the first computer to the second computer generally only the change data and the records of the first database that have been changed or added;

using the change data to determine which of the records of the first database have not been changed, added, or deleted since the previous synchronization;

using the result of that determination and the transferred records to reconstruct the content of the first database at the time of the previous synchronization;

performing a current synchronization using the reconstructed content of the first database, the history file containing records reflecting the contents of records of the databases at the time of the previous synchronization, and the second database

changing, adding, or deleting the records of the first database based on the result of the current synchronization;

changing, adding, or deleting the records of the second database based on the result of the current synchronization; and

changing, adding or deleting records in the history file using results of the current synchronization such that the history file contains records reflecting the contents of records of the first and second databases after the current synchronization.

2. The method of claim 1 wherein the records of the first and second databases are characterized respectively by first and second record structures, wherein the first record structure is different from the second record structure thereby making the first and second databases incompatible.

3. The computer implemented method of claim 2 wherein the change data indicates the most recent date and time of when the records were created or changed.

4. The computer implemented method of claim 2 wherein the change data comprises a flag set when the records are created or changed.

5. The computer implemented method of claim 2 wherein the first database provides further database generated data indicating which of the records were deleted since the previous synchronization, further comprising:

identifying records of the history file corresponding to the deleted records by performing a comparison of the further database generated data with the history file; and

completing the current synchronization using a result of the identification.

6. A computer program, resident on a computer readable medium, for synchronizing a first and a second database, wherein the first database is resident on a first computer and is capable of providing change data reflecting whether the records of the database have been changed, added, or deleted since the previous synchronization, wherein the second database is resident on a second computer different from the first computer, and wherein a history file reflecting the contents of records of the databases at the time of a prior synchronization is used to perform the synchronization, comprising instructions for:

determining whether the records of the first database have been changed, added, or deleted since a previous synchronization, based on change data reflecting whether the records of the first database have been changed, added, or deleted since the previous synchronization, the change data comprising database generated data for keeping track of whether the records of the first database have been changed, added, or deleted since a previous synchronization;

transferring from the first computer to the second computer generally only the change data and the records of the first database that have been changed or added;

using the change data to determine which of the records of the first database have not been changed, added, or deleted since the previous synchronization;

using the result of that determination and the transferred records to reconstruct the content of the first database at the time of the previous synchronization;

performing a current synchronization using the reconstructed content of the first database, the history file containing records reflecting the contents of records of the databases at the time of the previous synchronization, and the second database

changing, adding, or deleting the records of the first database based on the result of the current synchronization;

changing, adding, or deleting the records of the second database based on the result of the current synchronization; and

changing, adding or deleting records in the history file using results of the current synchronization such that the history file contains records reflecting the contents of records of the first and second databases after the current synchronization.

7. The computer program of claim 6 wherein the records of the first and second databases are charcterized respectively by first and second record structures, wherein the structure thereby making the first and second databases incompatible.

8. The computer program of claim 6 wherein the change data indicates the most recent date and time of when the records were created or changed.

9. The computer program of claim 6 wherein the chance data comprises a flag set when the recorda are created or changed.

10. The computer program of claim 6 wherein the first database provides further database generated data indicating which of the records were deleted since the previous synchronization, further comprising instructions for:

identifying records of the history file corresponding to the deleted records by performing a comparison of the further database generated data with the history file; and

completing the current synchronization using a result of the identification.