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

• US 20040030954A1
• Filed: 08/05/2003
• Published: 02/12/2004
• Est. Priority Date: 01/03/2000
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: OʼShaughnessy, Dan, Loaiza, Juan R., Kundu, Joydip, Cusson, Michael J., Frank, Richard L.
• Granted Patent: US 7,617,254 B2
• Time in Patent Office: Days
• US Class Current: 714/20
• 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 process for accessing database recovery logs comprising:

selecting recovery logs to access;

establishing a view of said recovery logs;

issuing a database statement to query said view; and

retrieving data from said recovery logs in response to said database statement.

2. The process of claim 1 further comprising:

generating a data dictionary snapshot; and

translating said data using said data dictionary snapshot.

3. The process of claim 2 in which said data is translated into an external data format.

4. The process of claim 1 in which time boundaries are established for said recovery logs.

5. The process of claim 1 in which date boundaries are established for said recovery logs.

6. The process of claim 1 in which said database statement is a SQL statement.

7. The process of claim 1 in which said recovery logs comprise an undo log.

8. The process of claim 1 in which said recovery logs comprise a redo log.

9. The process of claim 1 in which said view is a relational view comprising at least one row and at least one column.

10. The process of claim 1 in which said view is formed from a plurality of said recovery logs.

11. The process of claim 1 in which said view does not utilize database storage space.

12. The process of claim 1 in which said act of establishing a view is performed by constructing a virtual table using data from said recovery logs, wherein a schema of said virtual table is different than schema of said recovery logs.

13. The process of claim 12 in which said schema of said virtual table does not change if said schema of said virtual table does not change if said schema of said recovery logs change.

14. A computer program product that includes a medium usable by a processor, the 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:

determining recovery logs to access;

establishing a view of said recovery logs;

issuing a database statement to query said view; and

retrieving data from said recovery logs in response to said database statement.