SQL CHANGE TRACKING LAYER

• US 20080250073A1
• Filed: 04/05/2007
• Published: 10/09/2008
• Est. Priority Date: 04/05/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Novik, Lev, Chitre, Sudarshan A., Muralidhar, Subramanian, Nori, Anil Kumar, Sistla, Vijay Tandra, Mishra, Ambrish, Thangarathnam, Manikandan, Subramanian, Sankara, Oruganti, Laxmi Narsimha Rao, Raju, Sitaram C.V.
• Granted Patent: US 7,818,292 B2
• Time in Patent Office: Days
• US Class Current: 707/200
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27

Abstract

Systems and methods that track changes in a database via a change tracking layer that enables separation of change tracking and change enumeration. Such an arrangement enables multiple change enumeration and sync technologies over a single change tracking layer, while reducing amount of tracking information that are maintained.

Claims

1. A computer implemented system comprising the following computer executable components:

a data change tracking layer that enables separation of change tracking and change enumeration; and

a transaction identifier that tags changes, per table sync bookmark of the change tracking layer.

2. The computer implemented system of claim 1, the change tracking layer further comprising a transaction begin counter that monotonically increases to uniquely identify a transaction.

3. The computer implemented system of claim 2, the change tracking layer further comprising a transaction commit counter that is assigned to every committing transaction.

4. The computer implemented system of claim 1 further comprising a tombstone component that is maintained for DELETE tracking operation.

5. The computer implemented system of claim 1 further comprising a transaction commit sequence table that maps between a transaction begin counter value and a transaction commit counter value.

6. The computer implemented system of claim 1 further comprising a bookmark component that point to changes communicated to a sync partner.

7. The computer implemented system of claim 1 further comprising a sync layer that maintains a table of synchronization transaction.

8. The computer implemented system of claim 3 further comprising a metadata table that maintains values for the transaction begin counter and the transaction commit counter.

9. The computer implemented system of claim 1 further comprising an index that is modified only once per table per transaction.

10. A computer implemented method comprising the following computer executable acts:

tagging changes in a database by a single change tracking layer; and

separating change tracking and change enumeration by the single change tracking layer.

11. The computer implemented method of claim 10 further comprising enabling multiple change enumeration and sync technologies over the single change tracking layer.

12. The computer implemented method of claim 10 further comprising adding one entry to index when a single transaction INSERT ‘

N’

rows in a single table.

13. The computer implemented method of claim 10 further comprising employing two monotonically increasing counters for change tracking.

14. The computer implemented method of claim 10 further comprising serializing a row key upon row deletion.

15. The computer implemented method of claim 10 further comprising obtaining a value of a transaction begin counter and a transaction commit counter at time of enumerating changes.

16. The computer implemented method of claim 10 further comprising handling an index only once per table per transaction.

17. The computer implemented method of claim 10 further comprising identifying changes communicated to a sync partner.

18. The computer implemented method of claim 10 further comprising assigning a value for the transaction begin counter to an insert counter of a row during insert tracking.

19. The computer implemented method of claim 10 further comprising determining whether change counter of a row has higher value than last sent bookmark.

20. A computer implemented system comprising the following computer executable components:

means for separating change tracking and change enumeration for SQL transactions; and

means for tagging changes for a table.