RowID-based data synchronization for asynchronous table replication

• US 9,965,360 B2
• Filed: 03/13/2015
• Issued: 05/08/2018
• Est. Priority Date: 11/25/2014
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP SE
• Inventors: Lee, Juchang, Kim, Kyu-Hwan, Na, Hyoung-Jun, Park, Chang-Gyoo, Lee, Hyejeong
• Primary Examiner(s): Burke, Jeffrey A
• Assistant Examiner(s): Vu, Thong
• Application Number:
  US14/657,938
• Publication Number:
  US 20160147618A1
• Time in Patent Office: 1,152 Days
• Field of Search: 707625, 707685, 709227
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 11/1474 in transactions G06F16/20 takes precedence
• CPC Class Codes: G06F 11/1662 the resynchronized component or unit being a persistent storage device re-synchronization of failed mirror storage G06F11/2082; rebuild or reconstruction of parity RAID storage G06F11/1008
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27
• CPC Class Codes: G06F 16/2365 Ensuring data consistency and integrity
• CPC Class Codes: G06F 16/2379 Updates performed during online database operations; commit processing
• 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 16/273 Asynchronous replication or reconciliation
• CPC Class Codes: G06F 16/955 using information identifiers, e.g. uniform resource locators [URL]
• CPC Class Codes: G06F 2201/80 Database-specific techniques
• CPC Class Codes: G06F 2201/835 Timestamp

Abstract

Disclosed herein are system, method, and computer program product embodiments for synchronizing lost change between a source table and a replica table. An embodiment operates by detecting a restart at a source node or a replica node. Row-ID values of replication log entries are then compared to row-ID column values of rows at a replica table of the replica node. Replication errors at a source table or the replica table are then determined based on the row-ID comparison. The rows of the source table and the replica table are then updated based on the determination.

Claims

1. A computer implemented method for synchronizing lost changes between a source table and a replica table, comprising:

detecting, by at least one processor, a restart at a source node or a replica node, the source node having a source table and the replica node having a replica table;

comparing, by the at least one processor, a row of the source table to an associated row of the replica table based on a row-ID value of the row of the source table and a row-ID value of the associated row of the replica table, wherein the row-ID value of the row of the source table corresponds to a last write transaction on the row in the source table, and the row-ID value of the associated row of the replica table corresponds to a last write transaction on the row in the replica table;

determining, by the at least one processor, a replication error at the source table or the replica table based on the comparison; and

updating, by the at least one processor, the source table or the replica table based on the determination;

wherein at least one of the detecting, comparing, determining, and updating are performed by one or more computers.

2. The method of claim 1, wherein the restart at the source node or the replica node is caused by a respective crash of the source node or the replica node.

3. The method of claim 1, the updating further comprising:

performing no action based on the determination that the row-ID value of the row of source table is the same as the row-ID value of the associated row of the replica table.

4. The method of claim 1, the updating further comprising:

updating the associated row of the replica table with the row of source table based on the determination that the row-ID value of the row of source table is absent from the row-ID value of the associated row of the replica table.

5. The method of claim 1, the updating further comprising:

deleting the associated row of the replica table based on the determination that the row-ID value of the associated row of replica table is absent from the row-ID value of the row of the source table.

6. The method of claim 1, wherein the source table and the replica table are respectively stored using column based storage.

7. The method of claim 1, wherein the row-ID value of the row at the replica table comprises a monotonically increasing integer.

8. The method of claim 1, wherein the row-ID value of the row at the replica table is associated with a single database transaction.

9. A system, comprising:

a memory; and

at least one processor coupled to the memory and configured to;

detect a restart at a source node or a replica node, the source node having a source table and the replica node having a replica table;

compare a row of the source table to an associated row of the replica table based on a row-ID value of the row of the source table and a row-ID value of the associated row of the replica table, wherein the row-ID value of the row of the source table corresponds to a last write transaction on the row in the source table, and the row-ID value of the associated row of the replica table corresponds to a last write transaction on the row in the replica table;

determine a replication error at the source table or the replica table based on the comparison; and

update the source table or the replica table based on the determination.

10. The system of claim 9, wherein the restart at the source node or the replica node is caused by a respective crash of the source node or the replica node.

11. The system of claim 9, the at least one processor further configured to:

perform no action based on the determination that the row-ID value of the row of source table is the same as the row-ID value of the associated row of the replica table.

12. The system of claim 9, the at least one processor further configured to:

update the associated row of the replica table with the row of source table based on the determination that the row-ID value of the row of source table is absent from the row-ID value of the associated row of the replica table.

13. The system of claim 9, the at least one processor further configured to:

delete the associated row of the replica table based on the determination that the row-ID value of the associated row of replica table is absent from the row-ID value of the row of the source table.

14. The system of claim 9, wherein the source table and the replica table are respectively stored using column based storage.

15. A tangible computer-readable device having instructions stored thereon that, when executed by at least one computing device, causes the at least one computing device to perform operations comprising:

detecting a restart at a source node or a replica node, the source node having a source table and the replica node having a replica table;

comparing a row of the source table to an associated row of the replica table based on a row-ID value of the row of the source table and row-ID value of the associated row of the replica table, wherein the row-ID value of the row of the source table corresponds to a last write transaction on the row in the source table, and the row-ID value of the associated row of the replica table corresponds to a last write transaction on the row in the replica table;

determining a replication error at the source table or the replica table based on the comparison; and

updating the source table or the replica table based on the determination.

16. The computer-readable device of claim 15, wherein the restart at the source node or the replica node is caused by a respective crash of the source node or the replica node.

17. The computer-readable device of claim 15, the updating comprising:

performing no action based on the determination that the row-ID value of the row of source table is the same as the row-ID value of the associated row of the replica table.

18. The computer-readable device of claim 15, the updating comprising:

updating the associated row of the replica table with the row of source table based on the determination that the row-ID value of the row of source table is absent from the row-ID value of the associated row of the replica table.

19. The computer-readable device of claim 15, the updating comprising:

deleting the associated row of the replica table based on the determination that the row-ID value of the associated row of replica table is absent from the row-ID value of the row of the source table.

20. The computer-readable device of claim 15, wherein the source table and the replica table are respectively stored using column based storage.