System and method for updating external file referenced by database with transactional consistency using SQL

Patent metadata

Field	Value
Publication number	US-10235368-B2
Application number	US-13598202-A
Country	US
Kind code	B2
Filing date	Apr 30, 2002
Priority date	Jun 8, 2000
Publication date	Mar 19, 2019
Grant date	Mar 19, 2019

Abstract

A system and method for updating files in a file system that is linked to a database system which stores metadata pertaining to the files. Changes intended to be made to an original file are written to a replacement file, and when the user is ready to move the changes onto the original file, a database transaction is commenced. If the transaction commits, the replacement file is renamed to the original file and the file security attributes of the original file are applied. Otherwise, the rename operation does not take place, thereby ensuring consistency between the metadata in the dbms system and the file system data that is represented by the metadata.

First claim

We claim:

1. A computer program product comprising:
means for writing at least changes to at least one original file stored in a file system and having a name to at least one replacement file, the original file having metadata stored in a database system;
means for commencing a database transaction in the database system;
means for, responsive to a determination that the transaction commits,
designating, as the name of the replacement file, the name of the original file; and
removing the original file from the file system;

the designating means not designating, as the name of the replacement file, the name of the original file responsive to a determination that the transaction does not commit.

2. The computer program product of claim 1 , wherein responsive to a determination that the transaction does not commit, the original file is not removed from the file system.

3. The computer program product of claim 1 , further comprising means for setting, responsive to a determination that the transaction commits, at least one security attribute of the original file as a security attribute of the replacement file.

4. The computer program product of claim 1 , comprising means for providing at least one SQL interface to facilitate at least the designating and removing means.

5. The computer program product of claim 1 , comprising means for providing at least one SQL interface executable in at least one of an SQL UPDATE statement, and an SQL INSERT statement, the SQL interface providing at least one value to the database system.

6. The computer program product of claim 5 , comprising means for inserting the value into at least one data structure in the database system representing the metadata.

7. The computer program product of claim 6 , comprising means for sending a message from the database system to at least one manager associated with the file system to execute at least the designating means after operation of the means for inserting.

8. The computer program product of claim 7 , comprising means for validating the existence of the original and replacement files in response to the message.

9. The computer program product of claim 7 , comprising means for extracting security attributes from the original file in response to the message.

10. The computer program product of claim 9 , comprising means responsive to the server for making logged operations pertaining to the original and replacement files persistent.

11. The computer program product of claim 10 , comprising means for determining whether the means for making persistent is successful, and responsive to a determination that the means for making persistent is successful, undertaking at least one of: setting at least one security attribute of the replacement file to be a security attribute of the original file, and renaming the replacement file.

12. The computer program product of claim 7 , wherein the manager obtains an implicit lock on the original file, so that no one except a “super-user” can delete or change the original file.

13. The computer program product of claim 11 , comprising means for archiving the replacement file only after the replacement file has been renamed pursuant to a DLREPLACEMENTCONTENT operation.

14. The computer program product of claim 1 , wherein the designating and removing means establish at least in part a second phase of a commit, and responsive to a determination that a system crash occurs during the second phase, the product includes means for reexecuting at least the designating and removing means to restart the system.

15. The computer program product of claim 14 , further comprising:
means for, responsive to a determination that the replacement file is no longer present after the restart but the original file remains with a same timestamp and file size as the replacement file, returning “OK”, otherwise generating an error message; and
means for, responsive to a determination that the replacement file remains after the crash, copying file attributes from the original file to the replacement file, and renaming the replacement file but not deleting the original file.

16. A computer-implemented method for ensuring consistency between metadata stored in a database system and files stored in a file system and represented by the metadata, comprising:
writing at least changes to at least one original file having a name to at least one replacement file;
commencing a database transaction;
determining whether the transaction commits,
responsive to a determination that the transaction commits, designating, as the name of the replacement file, the name of the original file and
removing the original file from the file system;

responsive to a determination that the transaction does not commit, not designating, as the name of the replacement file, the name of the original file, wherein at least one manager is associated with the file system, the at least one manager receiving at least one message from the database system to execute at least the designating and removing, the manager also extracting security attributes from the original file in response to the message.

17. The method of claim 16 , wherein when the transaction does not commit, the original file is not removed from the file system.

18. The method of claim 16 , further comprising, responsive to a determination that the transaction commits, setting at least one security attribute of the original file as a security attribute of the replacement file.

19. The method of claim 16 , comprising providing at least one SQL interface to facilitate at least the designating and removing acts.

20. The method of claim 16 , comprising providing at least one SQL interface executable in at least one of: an SQL UPDATE statement, and an SQL INSERT statement, the SQL interface providing at least one value.

21. The method of claim 20 , comprising inserting the value into at least one data structure in the database system representing the metadata.

22. The method of claim 21 , wherein at least one server associated with the database system sends the at least one message to the at least one manager associated with the file system to execute at least the designating and removing acts after the act of inserting the value into the data structure.

23. The method of claim 22 , wherein the manager validates the existence of the original and replacement files in response to the message.

24. The method of claim 22 , wherein the manager, responsive to the server, makes logged operations pertaining to the original and replacement files persistent.

25. The method of claim 24 , wherein the manager determines whether the act of making persistent is successful, and if so, undertakes at least one of: setting at least one security attribute of the replacement file to be a security attribute of the original file, and executing the designating act.

26. A system comprising:
at least one database system storing metadata;
at least one file system storing files represented by the metadata; and
at least one SQL interface ensuring that files in the file system are not updated except when a transaction reflecting corresponding changes in the metadata commits in the database system;
at least one processor accessing instructions on a computer memory, the instructions when executed by the processor configuring the processor for:
determining whether the transaction commits;
responsive to a determina

Assignees

• Hsiao Hui I
• Hui Joshua Wai Ho
• Narang Inderpal Singh
• IBM

Inventors

• Hsiao Hui-I
• Hui Joshua Wai-Ho
• Narang Inderpal Singh

Classifications

• G06F16/10 Primary

  File systems; File servers · CPC title

• G06F17/30067 Primary

  Physics · mapped topic