Protocol agnostic database change tracking

• US 20060085485A1
• Filed: 10/19/2004
• Published: 04/20/2006
• Est. Priority Date: 10/19/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Shimshoni, Daniel S.
• Granted Patent: US 7,487,186 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users

Abstract

An efficient mechanism is provided to track and collect changes that have occurred in a database since a given point in time in a manner that is accessible and usable to systems that implement synchronization protocols, has a minimal impact on the performance of the database, and allows the identification of small pieces of data as changed.

Claims

1. A method for syncing data, comprising:

starting a sync session for a first sync partner;

modifying data associated with the first sync partner based on a first bitmap;

creating a second bitmap based on the first bitmap; and

clearing the first bitmap.

2. The method of claim 1, further comprising:

starting a sync session for a second sync partner;

determining changes to data associated with the second sync partner from the first bitmap and the second bitmap; and

modifying data associated with the second sync partner based on the determined changes.

3. The method of claim 2, wherein determining changes to data associated with the second sync partner comprises combining the first bitmap and the second bitmap.

4. The method of claim 1, wherein the first bitmap is a main bitmap and the second bitmap is a saved bitmap.

5. The method of claim 1, wherein creating the second bitmap comprises storing a copy of the first bitmap for at least one sync partner.

6. The method of claim 5, wherein storing the copy of the first bitmap comprises storing a field identifying the sync partner the copy is associated with.

7. The method of claim 1, further comprising generating the first bitmap, prior to modifying data associated with the first sync partner based on the first bitmap, by storing a plurality of bits, each bit associated with a column in a row and the value of each bit indicating the state of the associated column.

8. The method of claim 7, wherein the first bitmap further comprises a partner count field that identifies the number of sync partners.

9. The method of claim 1, further comprising incrementing a generation associated with the first sync partner after starting the sync session for the first sync partner.

10. A system for syncing data, comprising:

a first sync partner with an associated first data store;

a second sync partner with an associated second data store; and

a sync engine with a tracking layer, the tracking layer determining which data in the first data store should be sent to the first sync partner.

11. The system of claim 10, wherein the first sync partner is a computing device and the second sync partner is a database server.

12. The system of claim 10, further comprising a sync controller for controlling the sync engine, and a sync application for providing sync commands and instructions to the sync controller.

13. The system of claim 10, wherein the sync engine is comprised within the second sync partner.

14. The system of claim 10, wherein each of the first data store and the second data store has an associated generation.

15. The system of claim 14, wherein each generation comprises a logical timestamp that is local to the associated data store.

16. The system of claim 10, wherein the tracking layer comprises a plurality of system tables.

17. A sync engine, comprising:

a data store; and

a tracking layer, the tracking layer determining which data in a remote data store should be sent to the data store.

18. The sync engine of claim 17, wherein the tracking layer uses generation information in determining which data should be sent to the data store.

19. The sync engine of claim 17, wherein the tracking layer uses at least one bitmap in determining which data should be sent to the data store.

20. A computer-readable medium having stored thereon a data structure comprising:

a first bitmap comprising a partner count field, a size field, and a bit field, the bit field corresponding to the state of a columns in a row of data; and

a second bitmap comprising a partner identification field, a size field, and a bit field, for each of at least one sync partners.

21. The computer-readable medium of claim 20, wherein the bit field for the first bitmap comprises a plurality of bits, each bit associated with a column in a row and the value of each bit indicating the state of the associated column.

22. The computer-readable medium of claim 20, wherein the bit field of the first bitmap is cleared pursuant to a sync session.

23. The computer-readable medium of claim 22, wherein the bit field of the first bitmap is copied to the bit field of the second bitmap prior to being cleared.

24. A computer-readable medium having stored thereon computer-executable instructions for performing a method of syncing data, comprising:

starting a sync session for a first sync partner;

modifying data associated with the first sync partner based on a first bitmap;

creating a second bitmap based on the first bitmap; and

clearing the first bitmap.

25. The computer-readable medium of claim 24, further comprising computer-executable instructions for performing the steps of:

starting a sync session for a second sync partner;

determining changes to data associated with the second sync partner from the first bitmap and the second bitmap; and

modifying data associated with the second sync partner based on the determined changes.

26. The computer-readable medium of claim 25, wherein determining changes to data associated with the second sync partner comprises computer-executable instructions for combining the first bitmap and the second bitmap.

27. The computer-readable medium of claim 24, wherein the first bitmap is a main bitmap and the second bitmap is a saved bitmap.

28. The computer-readable medium of claim 24, wherein creating the second bitmap comprises computer-executable instructions for storing a copy of the first bitmap for at least one sync partner.

29. The computer-readable medium of claim 28, wherein storing the copy of the first bitmap comprises computer-executable instructions for storing a field identifying the sync partner the copy is associated with.

30. The computer-readable medium of claim 24, further comprising computer-executable instructions for generating the first bitmap, prior to modifying data associated with the first sync partner based on the first bitmap, by storing a plurality of bits, each bit associated with a column in a row and the value of each bit indicating the state of the associated column.

31. The computer-readable medium of claim 30, wherein the first bitmap further comprises a partner count field that identifies the number of sync partners.

32. The computer-readable medium of claim 24, further comprising computer-executable instructions for incrementing a generation associated with the first sync partner after starting the sync session for the first sync partner.