Protocol agnostic database change tracking

• US 7,487,186 B2
• Filed: 10/19/2004
• Issued: 02/03/2009
• 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.
• Primary Examiner(s): Alam; Hosain T
• Assistant Examiner(s): Ng; Amy
• Application Number:
  US10/968,539
• Publication Number:
  US 20060085485A1
• Time in Patent Office: 1,568 Days
• Field of Search: 707/200, 707/201, 707/203, 707/10, 707/204, 709/248
• 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 computer-implemented method for syncing data from a device to a plurality of sync devices on a per device basis, the device and the plurality of sync devices each having a data store for storing data, the device having multiple bitmaps facilitating syncing the data from the device to the plurality of sync devices, the method comprising:

starting a first sync session for syncing data from the device to a first sync device;

updating, based on a first bitmap stored in the device, data stored in the first sync device with the corresponding data stored in the device, the first bitmap comprising information indicative of change of the data when the data in the device is modified;

creating a second bitmap in the device by preserving the information stored in the first bitmap in the second bitmap;

clearing the first bitmap in the device after the first sync session is completed;

starting a second sync session for syncing the data from the device to a second sync device, wherein;

at least some of the data in the device has been modified before the second sync session; and

the information in the first bitmap is updated to indicate data change when the data in the device are modified;

determining changes to data to be updated in the second sync device based on a combination of the updated first bitmap and the second bitmap, wherein the combination comprises;

information from the second bitmap indicative of data change before the first sync session is performed; and

information from the first bitmap indicative of data change during a time period from the first sync session to the second sync session; and

updating data in the second sync device based on the determined changes.

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

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

4. The method of claim 3, wherein storing the copy of the first bitmap comprises storing a field identifying the sync device the copy is associated with.

5. The method of claim 1, further comprising generating the first bitmap, prior to modifying data associated with the first sync device 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.

6. The method of claim 5, wherein the first bitmap further comprises a device count field that identifies the number of sync device.

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

8. A computer-readable storage medium having stored thereon computer-executable instructions for performing a method of syncing data from a device to a plurality of sync devices on a per device basis, the instructions, when executed on a computing device, causing the computing device to perform a method, the method comprising:

starting a first sync session for syncing data from the device to a first sync device;

updating, based on a first bitmap stored in the device, data stored in the first sync device with the corresponding data stored in the device, the first bitmap comprising information indicative of change of the data when the data in the device is modified;

creating a second bitmap in the device by preserving the information stored in the first bitmap in the second bitmap;

clearing the first bitmap in the device after the first sync session is completed;

starting a second sync session for syncing the data from the device to a second sync device, wherein;

at least some of the data in the first device have been modified before the second sync session; and

the information in the first bitmap is updated to indicate data change when the data in the first device are modified;

determining changes to data to be updated in the second sync device based on a combination of the first bitmap and the second bitmap, wherein the combination comprises;

information from the second bitmap indicative of data change before the first sync session is performed; and

information from the first bitmap indicative of data change during a time period from the first sync session to the second sync session; and

updating data in the second sync device based on the determined changes.

9. The computer-readable storage medium of claim 8, wherein the first bitmap is a main bitmap and the second bitmap is a saved bitmap.

10. The computer-readable storage medium of claim 8, wherein creating the second bitmap comprises computer-executable instructions for storing a copy of the first bitmap for at least one sync device.

11. The computer-readable storage medium of claim 10, wherein storing the copy of the first bitmap comprises computer-executable instructions for storing a field identifying the sync device the copy is associated with.

12. The computer-readable storage medium of claim 8, wherein the method further comprises generating the first bitmap, prior to modifying data associated with the first sync device 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.

13. The computer-readable storage medium of claim 12, wherein the first bitmap further comprises a device count field that identifies the number of sync devices.

14. The computer-readable storage medium of claim 8, wherein the method further comprises incrementing a generation associated with the first sync device after starting the sync session for the first sync device.