Techniques for scalably accessing data in an arbitrarily large document by a device with limited resources

• US 20040088415A1
• Filed: 11/26/2002
• Published: 05/06/2004
• Est. Priority Date: 11/06/2002
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Sedlar, Eric, Chandrasekar, Sivasankaran, Murthy, Ravi, Agarwal, Nipun
• Granted Patent: US 7,308,474 B2
• Time in Patent Office: Days
• US Class Current: 709/226
• CPC Class Codes: G06F 12/126 with special data handling, e.g. priority of data or instructions, handling errors or pinning
• CPC Class Codes: G06F 16/86 Mapping to a database

Abstract

Techniques for accessing data that resides in a document on a computer-readable medium by a device with device resources of limited resource amount include determining usage for each portion of the document that consumes the device resources of a plurality of portions of the document. Each portion may be accessed independently of a different portion of the document. Based on the usage, a particular portion of the document is selected to cease consuming the device resources. The device resources consumed by the particular portion are released. The techniques allow a document-processing device with limited resources to scale up to process a large document that would otherwise exceed the available resources. This capability is an advantage when first inserting a large XML document, which cannot be fully manifested in available memory, as multiple loadable units into a database or other persistent store.

Claims

1. A method for accessing data that resides in a document on a computer-readable medium by a device with device resources of limited resource amount, the method comprising the steps of:

determining usage for each portion of the document that consumes the device resources of a plurality of portions of the document, wherein each portion may be accessed independently of a different portion of the document;

based on the usage, selecting a particular portion of the document to cease consuming the device resources; and

releasing the device resources consumed by the particular portion.

2. The method of claim 1, said step of selecting the particular portion comprising selecting the particular portion that is least recently used of a plurality of portions consuming the device resources.

3. The method of claim 1, wherein:

the method further comprises the step of determining whether a condition for releasing a resource is satisfied; and

said step of selecting the particular portion is performed only if it is determined that the condition for releasing a resource is satisfied.

4. The method of claim 3, wherein:

said step of determining usage further comprises determining total resource usage by all portions of the document that consume the device resources; and

the condition for releasing a resource includes that the total resource usage exceed a threshold resource amount that is less than the limited resource amount.

5. The method of claim 1, wherein:

said step of determining usage further comprises determining a number of uncompleted operations by the device on each portion that consumes device resources; and

said step of selecting the particular portion comprises determining that the number of uncompleted operations on the particular portion is less than a minimum number.

6. The method of claim 5, wherein the minimum number is one.

7. The method of claim 5, said step of selecting the particular portion further comprising the step of selecting the particular portion that is least recently used of a plurality of portions for which the number of uncompleted operations is less than the minimum number.

8. The method of claim 1, said step of releasing the device resources consumed by the particular portion comprising the steps of:

determining whether contents of the particular portion reside in persistent storage separately from a different portion of the document; and

if it is determined that the contents do not reside in persistent storage separately from a different portion, then writing the contents to persistent storage separately from a different portion before releasing the device resources consumed by the particular portion.

9. The method of claim 8, said step of releasing the device resources consumed by the particular portion further comprising, if it is determined that the contents do reside in persistent storage separately from a different portion, then performing the step of releasing the device resources consumed by the particular portion without writing the contents to persistent storage.

10. The method of claim 8, wherein the persistent storage is a file in a file system.

11. The method of claim 8, wherein the persistent storage is a database object in a database system.

12. The method of claim 1, further comprising the steps of:

determining hierarchical elements of the document from a type definition document associated with the document; and

determining the plurality of portions of the document based on the hierarchical elements.

13. The method of claim 1, wherein the document is an extensible markup language (XML) document.

14. The method of claim 12, wherein the document is an XML document and the type definition document is a document type definition (DTD) document.

15. The method of claim 12, wherein the document is an XML document and the type definition document is a XML schema document.

16. The method of claim 1, wherein the device resources comprise device fast memory.

17. The method of claim 8, said step of releasing the device resources further comprising the step of returning a reference to the particular portion in the persistent storage.

18. A computer-readable medium carrying one or more sequences of instructions for accessing data that resides in a document by a device with device resources of limited resource amount, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

determining usage for each portion of the document that consumes the device resources of a plurality of portions of the document, wherein each portion may be accessed independently of a different portion of the document;

based on the usage, selecting a particular portion of the document to cease consuming the device resources; and

releasing the device resources consumed by the particular portion.

19. The computer-readable medium of claim 18, said step of selecting the particular portion comprising selecting the particular portion that is least recently used of a plurality of portions consuming the device resources.

20. The computer-readable medium of claim 18, wherein:

execution of the one or more sequences of instructions by the one or more processors causes the one or more processors to perform the step of determining whether a condition for releasing a resource is satisfied; and

said step of selecting the particular portion is performed only if it is determined that the condition for releasing a resource is satisfied.

21. The computer-readable medium of claim 20, wherein:

said step of determining usage further comprises determining total resource usage by all portions of the document that consume the device resources; and

the condition for releasing a resource includes that the total resource usage exceed a threshold resource amount that is less than the limited resource amount.

22. The computer-readable medium of claim 18, wherein:

said step of determining usage further comprises determining a number of uncompleted operations by the device on each portion that consumes device resources; and

said step of selecting the particular portion comprises determining that the number of uncompleted operations on the particular portion is less than a minimum number.

23. The computer-readable medium of claim 22, wherein the minimum number is one.

24. The computer-readable medium of claim 22, said step of selecting the particular portion further comprising the step of selecting the particular portion that is least recently used of a plurality of portions for which the number of uncompleted operations is less than the minimum number.

25. The computer-readable medium of claim 18, said step of releasing the device resources consumed by the particular portion comprising the steps of:

determining whether contents of the particular portion reside in persistent storage separately from a different portion of the document; and

if it is determined that the contents do not reside in persistent storage separately from a different portion, then writing the contents to persistent storage separately from a different portion before releasing the device resources consumed by the particular portion.

26. The computer-readable medium of claim 25, said step of releasing the device resources consumed by the particular portion further comprising, if it is determined that the contents do reside in persistent storage separately from a different portion, then performing the step of releasing the device resources consumed by the particular portion without writing the contents to persistent storage.

27. The computer-readable medium of claim 25, wherein the persistent storage is a file in a file system.

28. The computer-readable medium of claim 25, wherein the persistent storage is a database object in a database system.

29. The computer-readable medium of claim 18, wherein execution of the one or more sequences of instructions by the one or more processors further causes the one or more processors to perform the steps of:

determining hierarchical elements of the document from a type definition document associated with the document; and

determining the plurality of portions of the document based on the hierarchical elements.

30. The computer-readable medium of claim 18, wherein the document is an extensible markup language (XML) document.