Persistence and initialization of synchronization state for serialized data log replay in database systems

• US 10,698,921 B2
• Filed: 02/28/2017
• Issued: 06/30/2020
• Est. Priority Date: 02/28/2017
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP SE
• Inventors: Florendo, Colin, Muehle, Michael, Glebe, Thorsten, Blanco, Rolando, Gottipati, Chaitanya, Basak, Nirvik, Radestock, Gunter
• Primary Examiner(s): Choi, Yuk Ting
• Application Number:
  US15/445,505
• Publication Number:
  US 20180246947A1
• Time in Patent Office: 1,218 Days
• CPC Class Codes: G06F 16/2343 Locking methods, e.g. distributed locking or locking implementation details
• CPC Class Codes: G06F 16/2379 Updates performed during online database operations; commit processing
• CPC Class Codes: G06F 16/273 Asynchronous replication or reconciliation

Abstract

A computer implemented method for initializing a secondary database system includes receiving table state information from a primary database system at a secondary database system. The table state information includes information identifying which tables had an open operation during a savepoint event. Metadata associated with the tables is parsed to identify table state information from the metadata and a lock is created for each table identified as having an open operation during the savepoint event. Afterwards, log transaction information is sequentially parsed. Related apparatus, systems, techniques and articles are also described.

Claims

1. A computer implemented method comprising:

receiving table state information from a primary database system at a secondary database system, the table state information comprising information identifying which tables had an open data definition language (DDL) query during a savepoint event;

parsing metadata associated with the tables to identify table state information from the metadata;

creating, without a record of a start of the DDL query, a lock for each table identified as having an open DDL query during the savepoint event after replaying a corresponding DDL Start (DDLStart) transaction log record;

parsing log transaction information sequentially;

returning a table that is locked to an unlocked state after replaying a DDL End (DDLEnd) transaction log record; and

initializing the secondary database after the savepoint event but before a subsequent savepoint event;

wherein a DDL operation scope object on a DDL operation thread stack controls writing of the DDLStart and DDLEnd transaction log records so that the DDLEnd is always written regardless of how the DDL operation thread exits.

2. The method of claim 1, wherein the savepoint event occurs during execution of an operation comprising a plurality of sub-operations.

3. The method of claim 2, wherein the table state information comprises a 32 bit unsigned integer.

4. The method of claim 1, wherein the log transaction information includes transactions since the savepoint event.

5. The method of claim 1, wherein the log transaction information comprises a transaction to terminate the lock created for each table identified as having an open operation during the savepoint event.

6. The method of claim 1, wherein the method is executed during initialization of the secondary database system.

7. The method of claim 1, wherein the log transaction information is generated by the primary database system based on queries received by the primary database system since the savepoint event.

8. The method of claim 1, wherein the primary database system and the secondary database system are configured to operate in a load balancing operation.

9. The method of claim 1, wherein the primary database system and the secondary database system are in memory database (IMDB) systems and the secondary database system is configured as a back-up database system.

10. The method of claim 1, wherein the primary database system and the secondary database system are column oriented database systems.

12. The system of claim 1, wherein the savepoint event occurs during execution of an operation comprising a plurality of sub-operations.

13. The method of claim 12, wherein the table state information comprises a 32 bit unsigned integer.

11. A system comprising:

a processor; and

a non-transitory computer readable media having computer executable instructions stored therein, which, when executed by the processor, causes the system to perform operations comprising;

receiving table state information from a primary database system at a secondary database system, the table state information comprising information identifying which tables had an open data definition language (DDL) query during a savepoint event;

parsing metadata associated with the tables to identify table state information from the metadata;

creating, without a record of a start of the DDL query, a lock for each table identified as having an open DDL query during the savepoint event after replaying a corresponding DDL Start (DDLStart) transaction log record;

parsing log transaction information sequentially;

returning a table that is locked to an unlocked state after replaying a DDL End (DDLEnd) transaction log record; and

initializing the secondary database after the savepoint event but before a subsequent savepoint events;

wherein a DDL operation scope object on a DDL operation thread stack controls writing of the DDLStart and DDLEnd transaction log records so that the DDLEnd is always written regardless of how the DDL operation thread exits.

14. The system of claim 11, wherein the log transaction information includes transactions since the savepoint event.

15. The system of claim 11, wherein the log transaction information comprises a transaction to terminate the lock created for each table identified as having an open operation during the savepoint event.

16. The system of claim 11, wherein the method is executed during initialization of the secondary database system.

17. The system of claim 11, wherein the log transaction information is generated by the primary database system based on queries received by the primary database system since the savepoint event.

18. The system of claim 11, wherein the primary database system and the secondary database system are configured to operate in a load balancing operation.

19. The system of claim 11, wherein the primary database system and the secondary database system are in memory database (IMDB) systems and the secondary database system is configured as a back-up database system.

20. The system of claim 11, wherein the primary database system and the secondary database system are column oriented database systems.