Method and mechanism for relational access of recovery logs in a database system

• US 7,617,254 B2
• Filed: 08/05/2003
• Issued: 11/10/2009
• Est. Priority Date: 01/03/2000
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Loaiza, Juan R., O'Shaughnessy, Dan, Frank, Richard L., Kundu, Joydip, Cusson, Michael J.
• Primary Examiner(s): Ly; Cheyne D
• Application Number:
  US10/635,708
• Publication Number:
  US 20040030954A1
• Time in Patent Office: 2,289 Days
• Field of Search: 707/100, 707/102, 707/1, 707/2, 707/3, 707/4, 707/5, 707/101, 707/202, 714/20
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99934 Query formulation, input preparation, or translation
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

The present invention is directed to a method and mechanism for accessing recovery log information in a database system. The data stored in the recovery log is presented as a relational database “view,” which can be queried and accessed using relational database statements even though the underlying recovery log data may be stored in a non-relational format. According to an aspect of the invention, the recovery log data is thus encapsulated by the view presented to users of that data.

Claims

1. A method of accessing database recovery logs of a database, said method comprising:

selecting at least one of said database recovery logs to access, in which the at least one of the database recovery logs contains information for restoring the database to a specific state;

establishing a view of the at least one of said database recovery logs;

insulating said view from a format of the at least one of said database recovery logs;

issuing a database statement to query said view;

retrieving data from at least one of said database recovery logs in response to said database statement; and

displaying a result of the act of retrieving the data or storing the result in a tangible computer readable medium.

2. The method of claim 1, wherein insulating said view comprises:

generating a data dictionary snapshot; and

translating said data using said data dictionary snapshot.

3. The method of claim 2, wherein said data is translated into an external data format.

4. The method of claim 1, wherein time and/or date boundaries are established for said recovery logs.

5. The method of claim 1, wherein said database statement is a SQL statement.

6. The method of claim 1, wherein said recovery logs comprise an undo log and/or a redo log.

7. The method of claim 1, wherein said view is a relational view comprising at least one row and at least one column.

8. The method of claim 1, wherein said view is formed from a plurality of said recovery logs.

9. The method of claim 1, wherein said view does not utilize database storage space.

10. The method of claim 1, wherein establishing a view comprises a virtual table using data from the at least one of said database recovery logs, wherein a format of said virtual table is independent of the format of the at least one of said database recovery logs.

11. The method of claim 1, wherein a format of the view remains unchanged without modifying a query statement corresponding to the view when the format of the at least one of said recovery logs changes.

31. The method of claim 1, wherein a format of the view remains unchanged without modifying a query statement corresponding to the view when the format of the at least one of said recovery logs changes.

12. A computer program product that includes a medium usable by a processor, said medium having stored thereon a sequence of instructions which, when executed by said processor, causes said processor to execute a process for accessing database recovery logs, said process comprising:

selecting at least one of said database recovery logs to access, in which the at least one of the database recovery logs contains information for restoring the database to a specific state;

establishing a view of the at least one of said database recovery logs;

insulating said view from a format of the at least one of said database recovery logs;

issuing a database statement to query said view;

retrieving data from at least one of said database recovery logs in response to said database statement; and

displaying a result of the act of retrieving the data or storing the result in a tangible computer readable medium.

13. The computer program product of claim 12, wherein insulating said view comprises:

generating a data dictionary snapshot; and

translating said data using said data dictionary snapshot.

14. The computer program product of claim 13, wherein said data is translated into an external data format.

15. The computer program product of claim 12, wherein time and/or date boundaries are established for said recovery logs.

16. The computer program product of claim 12, wherein said recovery logs comprise an undo log and/or a redo log.

17. The computer program product of claim 12, wherein said view is a relational view comprising at least one row and at least one column.

18. The computer program product of claim 12, wherein said view is formed from a plurality of said recovery logs.

19. The computer program product of claim 12, wherein said view does not utilize database storage space.

20. The computer program product of claim 12, wherein establishing a view comprises a virtual table using data from the at least one of said database recovery logs, wherein a format of said virtual table is independent of the format of the at least one of said database recovery logs.

21. The computer program product of claim 12, wherein a format of the view remains unchanged without modifying a query statement corresponding to the view when the format of the at least one of said recovery logs changes.

22. A system for accessing database recovery logs, said system comprising:

means for selecting at least one of said database recovery logs to access;

means for establishing a view of the at least one of said database recovery logs;

means for insulating said view from a format of the at least one of said database recovery logs;

means for issuing a database statement to query said view;

means for retrieving data from at least one of said database recovery logs in response to said database statement; and

a display apparatus configured for displaying a result of the act of retrieving the data or a computer readable medium or a storage device configured for storing the result.

23. The system of claim 22, wherein means for insulating said view comprises:

means for generating a data dictionary snapshot; and

means for translating said data using said data dictionary snapshot.

24. The system of claim 23, wherein said data is translated into an external data format.

25. The system of claim 22, wherein time and/or date boundaries are established for said recovery logs.

26. The system of claim 22, wherein said recovery logs comprise an undo log and/or a redo log.

27. The system of claim 22, wherein said view is a relational view comprising at least one row and at least one column.

28. The system of claim 22, wherein said view is formed from a plurality of said recovery logs.

29. The system of claim 22, wherein said view does not utilize database storage space.

30. The system of claim 22, wherein the view in the means for establishing a view comprises a virtual table using data from the at least one of said database recovery logs, wherein a format of said virtual table is independent of the format of the at least one of said database recovery logs.