Maintenance of link level consistency between database and file system

• US 20060253502A1
• Filed: 05/06/2005
• Published: 11/09/2006
• Est. Priority Date: 05/06/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Yan, Kangrong, Raman, Balan Sethu, Rajan, Rajeev B.
• Granted Patent: US 8,145,686 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2308 Concurrency control transaction processing G06F9/466
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27

Abstract

Methods and computer-readable media for maintaining transactional link-level consistency between a database and a file system. A file system change is logged in a record of a database log and a file corresponding to the file system change is created in a file system folder. During a restart recovery process, an analysis operation and a conditional redo operation are performed based on the database log, and a conditional redo operation and an undo operation are performed based on the files in the file system folder. An undo operation is then performed based on the database log.

Claims

1. A method of maintaining transactional link-level consistency between a database and a file system, comprising:

logging a file system change in a record of a database log;

creating a file corresponding to the file system change in a file system log folder; and

, in a restart recovery,

performing an analysis operation and a conditional redo operation based on the database log;

performing a conditional redo operation and an undo operation based on the file system log; and

performing an undo operation based on the database log.

2. The method of claim 1, further comprising creating a filename associated with the file.

3. The method of claim 2, wherein the filename comprises a file system object name, a Log Sequence Number, a transaction identifier and an operation descriptor corresponding to the file system change.

4. The method of claim 2, further comprising recording a Log Sequence Number of the database log record in the filename, wherein the Log Sequence Number corresponds to the file system change.

5. The method of claim 1, wherein said logging and creating steps take place prior to execution of the file system change.

6. The method of claim 5, wherein said logging step takes place prior to said creating step.

7. The method of claim 1, wherein the database log and the file system log folder comprise a plurality of records and files, respectively, and further comprising:

recording a Log Sequence Number associated with the file system change in one of the plurality of records;

selecting one of the plurality of records; and

wherein said performing a conditional redo operation step further comprises comparing a maximum Log Sequence Number associated with the file system change to a Log Sequence Number associated with the selected record.

8. The method of claim 7, wherein said conditional redo operation is performed on the file if the Log Sequence Number associated with the selected record is greater than or equal to the maximum Log Sequence Number associated with the file system change.

9. The method of claim 1, wherein the file system change is made to Binary Large Object data that is stored in the file system.

10. The method of claim 1, wherein the file system change is made to a file or a directory of the file system.

11. The method of claim 1, wherein the steps of performing an analysis operation, conditional redo operation and undo operation on the database log are performed in accordance with Algorithms for Recovery and Isolation Exploiting Semantics (ARIES).

12. The method of claim 1, wherein the steps of performing a conditional redo operation and an undo operation on the file are performed in accordance with ARIES.

13. The method of claim 1, wherein the file is a first file, and further comprising performing a file system flush operation by creating and flushing a second file.

14. A method of maintaining transactional link-level consistency between a database and a file system, comprising:

logging a file system change in a record of a database log having a plurality of records;

assigning a first Log Sequence Number to the record;

creating a file having a filename and corresponding to the file system change in a file system log folder having a plurality of Log Sequence Numbers;

encoding the first Log Sequence Number in the filename; and

, in a restart recovery,

performing an analysis operation and a conditional redo operation on the database log;

selecting one of the plurality of records;

comparing a Log Sequence Number associated with the selected record to a maximum Log Sequence Number associated with the file system change;

redoing a log record if the Log Sequence Number associated with the selected record is greater than or equal to the maximum Log Sequence Number associated with the file system change;

performing an undo operation based on the file system log folder; and

performing an undo operation based on the database log.

15. The method of claim 14, wherein the filename further comprises a file system object name, a transaction identifier and an operation descriptor corresponding to the file system change.

16. The method of claim 14, wherein said logging and creating steps take place prior to execution of the file system change, and wherein said logging step takes place prior to said creating step.

17. The method of claim 14, wherein the file system change is made to Binary Large Object data that is stored in the file system.

18. The method of claim 14, wherein the steps of performing an analysis operation, conditional redo operation and undo operation based on the database log and performing a conditional redo operation and an undo operation based on the file system log are performed in accordance with Algorithms for Recovery and Isolation Exploiting Semantics (ARIES).

19. The method of claim 14, wherein the file is a first file, and further comprising performing a file system flush operation by creating and flushing a second file.

20. A computer-readable medium having computer-executable instructions for performing a method of maintaining transactional link-level consistency between a database and a file system, the method comprising:

logging a file system change in a record of a database log;

creating a file corresponding to the file system change in a file system folder; and

, in a restart recovery,

performing an analysis operation and a conditional redo operation based on the database log;

performing a conditional redo operation and an undo operation based on the file system log folder; and

performing an undo operation on the database log.