Dynamic redistribution of a distributed memory index when individual nodes have different lookup indexes

• US 20050240595A1
• Filed: 11/30/2004
• Published: 10/27/2005
• Est. Priority Date: 04/26/2004
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Chandrasekaran, Sashikanth
• Granted Patent: US 7,962,453 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/1774 Locking methods, e.g. locking methods for file systems allowing shared and concurrent access to files
• CPC Class Codes: G06F 16/2246 Trees, e.g. B+trees

Abstract

Techniques for performing window-by-window remastering are described, in which the mechanism used by nodes to determine the resource-to-window mapping is separated from the mechanism used by the nodes to access resource information. For example, all nodes of a multiple-node system may use the same hash function to determine which resources are involved in a remastering window. However, the resource indexes employed by the nodes to access resource information need not use that same hash function. For example, in nodes where the resource indexes are hash indexes, different nodes may use different hash functions. Further, some or all of the nodes may use mechanisms other than hash indexes to access the resource information.

Claims

1. A method of redistributing responsibilities relating to resources in a multiple-node system, the method comprising the steps of:

redistributing responsibilities relating to resources between a plurality of nodes in the multiple-node system on a window-by-window basis, wherein only those resources that are mapped to a particular window have their responsibilities changed during the time period associated with the particular window;

each node of the plurality of nodes determining the mapping between resources and windows using the same hash function as each other node of said plurality of nodes;

wherein the plurality of nodes includes a particular node that uses a resource index to access resource information associated with the resources for which the particular node is responsible; and

wherein the particular node does not use said same hash function to locate resource information within said resource index.

2. The method of claim 1 wherein the resource index is a hash index, and the particular node uses a different hash function to locate resource information within said resource index.

3. The method of claim 1 wherein the resource index is a b-tree index.

4. The method of claim 1 wherein:

the particular node is a first node of the plurality of nodes;

each node of the plurality of nodes has a resource index used to access resource information associated with the resources for which the node is responsible;

the resource index of the first node is a first hash index that has a first hash table of a first size;

the plurality of nodes includes a second node whose resource index is a second hash index that has a second hash table of a second size;

the first size is different from the second size; and

the first size and the second size are selected independent of each other.

5. The method of claim 1 wherein:

the particular node is a first node of the plurality of nodes;

each node of the plurality of nodes has a resource index used to access resource information associated with the resources for which the node is responsible;

the resource index of the first node is a first hash index that uses a first hash function to access resources in a first hash table;

the plurality of nodes includes a second node whose resource index is a second hash index that uses a second hash function to access resources in a second hash table; and

the first hash function is different than the second hash function.

6. The method of claim 1 wherein:

the multiple-node system is a multiple-node database system;

the resources are resources managed by the database system; and

the particular node uses the resource index to access lock information associated with the resources for which the particular node is responsible.

7. The method of claim 6 wherein the resource index and the lock information are stored in volatile memory within the particular node.

8. The method of claim 1 wherein:

the multiple-node system is a multiple-node file system;

the resources include files managed by the file system; and

the particular node uses the resource index to access file information associated with the files for which the particular node is responsible.

9. The method of claim 1 wherein the resource index is a name-value lookup directory.

10. The method of claim 1 further comprising partitioning said resource index based on said same hash function.

11. The method of claim 1 wherein the step of redistributing responsibilities relating to resources between a plurality of nodes in the multiple-node system on a window-by-window basis includes remastering the resources between the plurality of nodes on a window-by-window basis.

12. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 1.

13. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 2.

14. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 3.

15. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 4.

16. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 5.

17. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 6.

18. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 7.

19. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 8.

20. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 9.

21. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 10.

22. A computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, causes the one or more processors to perform the method recited in claim 11.