Apparatus, system, and method for efficient recovery of a database from a log of database activities

• US 20060031267A1
• Filed: 08/04/2004
• Published: 02/09/2006
• Est. Priority Date: 08/04/2004
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Moore, David Wayne, Lim, Victor King, Perry, F. Stephen
• Application Number:
  US10/911,803
• Publication Number:
  US 20060031267A1
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 2201/80 Database-specific techniques

Abstract

An apparatus, system, and method are disclosed for efficient recovery of a database from a log of database activities. A log of database activities is filtered into a first sequential data set. The remainder portion of the log is sorted into a second sequential data set. The first sequential data set and the second sequential data set are merged and written to the database. Allowing the sequential records to bypass a sort operation reduces the amount of time and the system resource overhead required for database recovery.

Claims

1. An apparatus for efficient recovery of a database from a log of database activities, the apparatus comprising:

a filtering module configured to separate log records from a log data set for a database into a first sequential data set;

a sorting module configured to sort the remaining log data set into a second sequential data set;

a merging module configured to merge the first sequential data set and the second sequential data set into a recovery data set; and

a writing module configured to write the recovery data set to the database.

2. The apparatus of claim 1, wherein the filter module is further configured to filter the log records that satisfy an indirect sequence identifier.

3. The apparatus of claim 2, wherein the indirect sequence identifier identifies a database application that originated the log record.

4. The apparatus of claim 1, further comprising a verification module configured to verify a sequence of the first sequential data set.

5. The apparatus of claim 4, wherein the verification module is further configured to compare a direct sequence identifier of a log record with a direct sequence identifier for a previous log record in the first sequential data set, and sends non-sequential log records to the unsorted log data set.

6. The apparatus of claim 1, wherein the sorting module is further configured to determine a sequence for the log data set based on a direct sequence identifier for each log record, the sequence identifier comprising at least one attribute selected from a group consisting of a database data set identifier, a relative byte address identifier, a data set sequence number, a lock sequence number, and a time stamp.

7. The apparatus of claim 1, wherein the merging module is further configured to sequentially merge log records from the first sequential data set and from the second sequential data set into a database.

8. The apparatus of claim 7, wherein the sequence is determined by a direct sequence identifier within the log data records.

9. The apparatus of claim 1, wherein the writing module is further configured to write the recovery data set to the database in a single pass.

10. The apparatus of claim 1, wherein the merging module is further configured to selectively pass records from the first sequential data set and the second sequential data set, in response to a sequence defined by a direct sequence identifier.

11. A system to efficiently recover a database from a log of database activities, the system comprising:

a database configured to process concurrent sequential updates and non-sequential updates;

a log data set comprising log records associated with sequential updates and non-sequential updates;

a recovery apparatus configured to sort the log data set, the recovery apparatus comprising;

a filtering module configured to separate log records from a log data set for a database into a first sequential data set;

a sorting module configured to sort the remaining log data set into a second sequential data set;

a merging module configured to merge the first sequential data set and the second sequential data set into a recovery data set; and

a writing apparatus configured to write the recovery data set to the database.

12. The system of claim 11, wherein the recovery apparatus is further configured to filter the log records that satisfy an indirect sequence identifier.

13. The system of claim 12, wherein the indirect sequence identifier identifies a database application that originated the log record.

14. The system of claim 13, further configured to verify a sequence of the first sequential data set.

15. The system of claim 14, further configured to compare a direct sequence identifier of a log record with a direct sequence identifier for a previous log record in the first sequential data set, and sends non-sequential log records to the unsorted log data set.

16. The system of claim 15, wherein the recovery apparatus is further configured to determine a sequence for the log data set based on a direct sequence identifier for each log record, the sequence identifier comprising at least one attribute selected from a group consisting of a database data set identifier, a relative byte address identifier, a data set sequence number, a lock sequence number, and a time stamp.

17. The system of claim 16, wherein the recovery apparatus is further configured to sequentially merge log records from the first sequential data set and from the second sequential data set into a database.

18. The system of claim 17, wherein the sequence is determined by a direct sequence identifier within the log data records.

19. The system of claim 18, wherein the writing apparatus is further configured to write the recovery data set to the database in a single pass.

20. The system of claim 19, wherein the recovery apparatus is further configured to selectively pass records from the first sequential data set and the second sequential data set, in response to a sequence defined by a direct sequence identifier.

21. A signal bearing medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for efficient recovery of a database from a log of database activities, the operations comprising:

an operation to separate log records from a log data set for a database into a first sequential data set;

an operation to sort the remaining log data set into a second sequential data set;

an operation to merge the first sequential data set and the second sequential data set into a recovery data set; and

an operation to write the recovery data set to the database.

22. The signal bearing medium of claim 21, wherein the operation to filter log records is further configured to filter the log records that satisfy an indirect sequence identifier.

23. The signal bearing medium of claim 22, wherein the indirect sequence identifier identifies a database application that originated the log record.

24. The signal bearing medium of claim 21, wherein the instructions further comprise an operation to verify a sequence of the first sequential data set.

25. The signal bearing medium of claim 24, wherein the operation to verify a sequence compares a direct sequence identifier of a log record with a direct sequence identifier for a previous log record in the first sequential data set, and sends non-sequential log records to the unsorted log data set.

26. The signal bearing medium of claim 21, wherein the sort operation is determines a sequence for the log data set based on a direct sequence identifier for each log record, the sequence identifier comprising at least one attribute selected from a group consisting of a database data set identifier, a relative byte address identifier, a data set sequence number, a lock sequence number, and a time stamp.

27. The signal bearing medium of claim 21, wherein the merge operation further comprises sequentially merging log records from the first sequential data set and from the second sequential data set into a database.

28. The signal bearing medium of claim 27, wherein the sequence is determined by a direct sequence identifier within the log data records.

29. The signal bearing medium of claim 21, wherein the operation to write further comprises writing the recovery data set to the database in a single pass.

30. The signal bearing medium of claim 21, wherein the operation to merge further comprises selectively passing records from the first sequential data set and the second sequential data set, in response to a sequence defined by a direct sequence identifier.