System for allowing object metadata to be shared between cursors for concurrent read write access

• US 7,698,310 B2
• Filed: 05/13/2005
• Issued: 04/13/2010
• Est. Priority Date: 05/14/2004
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Shankar, Shrikanth, Green, Russell John, Basu, Subhransu
• Primary Examiner(s): NGUYEN, CAM LINH T
• Application Number:
  US11/129,617
• Publication Number:
  US 20060004755A1
• Time in Patent Office: 1,796 Days
• Field of Search: 707/203, 707/8, 707/100, 707/200, 707/201, 707/1
• US Class Current: 1/1
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching
• CPC Class Codes: G06F 21/6218 to a system of files or objects, e.g. local or distributed file system or database
• CPC Class Codes: G06F 2221/2147 Locking files
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

A system, method, computer program and article of manufacture for sharing metadata among cursors is provided. A metadata object marked as a versioned object can have multiple versions. Program units can share these versions of object metadata as opposed to copying the non-versioned object metadata into their memory. These program units may contain a pointer to an object'"'"'s metadata but are otherwise void of the metadata information for the object. A locking protocol for the metadata ensures concurrency control and triggers dependency tracking. A locking protocol for the cursors controls cursor dependency status.

Claims

1. A method of sharing metadata, at least part of the method implemented using a processor, the method comprising:

receiving a plurality of requests to access a resource;

creating a program unit for each of the plurality of requests;

creating an execution representation of metadata for the resource using the processor, wherein the metadata comprises partitioning information for the resource, and the execution representation of the metadata allows sharing of the metadata without storing multiple copies of instances of the metadata; and

sharing the execution representation of the metadata among the plurality of program units.

2. The method of claim 1, wherein the metadata for the resource is a versioned object.

3. The method of claim 2, wherein creating the execution representation comprises:

creating a plurality of execution representation versions of the resource'"'"'s metadata, the plurality of program units having access to the plurality of execution representation version without storing the metadata in the memory of each program unit.

4. The method of claim 3, wherein sharing the execution representation comprises:

establishing each of the plurality of program units as dependents of the execution representation version.

5. The method of claim 4, wherein each of the plurality of execution representation versions is maintained while it is in use or while it has a dependent.

6. The method of claim 5, wherein each of the execution representation versions of metadata is eliminated when no longer in use and when it no longer has dependents.

7. The method of claim 1, wherein creating the execution representation comprises:

accessing a persistent version of the resource'"'"'s metadata;

locking the persistent version;

creating an execution representation version of the resource'"'"'s metadata; and

unlocking the persistent version.

8. A system of sharing metadata, comprising:

means for receiving a plurality of requests to access a resource;

means for creating a program unit for each of the plurality of requests;

means for creating an execution representation of metadata for the resource on a volatile or non-volatile computer readable medium, wherein the metadata comprises partitioning information for the resource, and the execution representation of the metadata allows sharing of the metadata without storing multiple copies of instances of the metadata; and

means for sharing the execution representation of the metadata among the plurality of program units.

9. The system of claim 8, wherein the metadata for the resource is a versioned object.

10. The system of claim 9, wherein the means for creating the execution representation comprises:

means for creating a plurality of execution representation versions of the resource'"'"'s metadata object, the plurality of program units having access to the plurality of execution representation version without storing the metadata object in the memory of each program unit.

11. The system of claim 10, wherein the means for sharing the execution representation comprises:

means for establishing each of the plurality of program units as dependents of the execution representation version.

12. The system of claim 11, wherein each of the plurality of execution representation versions is maintained while it is in use or while it has a dependent.

13. The system of claim 12, wherein each of the execution representation versions of metadata is eliminated when no longer in use and when it no longer has dependents.

14. The system of claim 8, wherein the means for creating the execution representation comprises:

means for accessing a persistent version of the resource'"'"'s metadata;

means for locking the persistent version;

means for creating an execution representation version of the resource'"'"'s metadata; and

means for unlocking the persistent version.

15. A computer program product embodied on a volatile or non-volatile computer readable medium, the computer readable medium having stored thereon a sequence of instructions which, when executed by a processor, causes the processor to execute a method for sharing metadata, the method comprising:

receiving a plurality of requests to access a resource;

creating a program unit for each of the plurality of requests;

creating an execution representation of metadata for the resource, wherein the metadata comprises partitioning information for the resource, and the execution representation of the metadata allows sharing of the metadata without storing multiple copies of instances of the metadata; and

sharing the execution representation of the metadata among the plurality of program units.

16. The computer program product of claim 15, wherein the metadata for the resource is a versioned object.

17. The computer program product of claim 16, wherein creating the execution representation comprises:

creating a plurality of execution representation versions of the resource'"'"'s metadata, the plurality of program units having access to the plurality of execution representation version without storing the metadata object in the memory of each program unit.

18. The computer program product of claim 17, wherein sharing the execution representation comprises:

establishing each of the plurality of program units as dependents of the execution representation version.

19. The computer program product of claim 18, wherein each of the plurality of execution representation versions is maintained while it is in use or while it has a dependent.

20. The computer program product of claim 19, wherein each of the execution representation versions of metadata is eliminated when no longer in use and when it no longer has dependents.

21. The computer program product of claim 15, wherein creating the execution representation comprises:

accessing a persistent version of the resource'"'"'s metadata;

locking the persistent version;

creating an execution representation version of the resource'"'"'s metadata; and

unlocking the persistent version.