Method and system for flexible sectioning of XML data in a database system

• US 20050228818A1
• Filed: 03/18/2005
• Published: 10/13/2005
• Est. Priority Date: 04/09/2004
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Sedlar, Eric, Thusoo, Ashish, Chandrasekar, Sivasankaran, Murthy, Ravi, Agarwal, Nipun, Mukkamalla, Sreedhar
• Granted Patent: US 7,461,074 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/81 Indexing, e.g. XML tags; Data structures therefor; Storage structures
• CPC Class Codes: G06F 16/86 Mapping to a database
• CPC Class Codes: G06F 40/123 Storage facilities
• CPC Class Codes: G06F 40/131 Fragmentation of text files, e.g. creating reusable text-blocks; Linking to fragments, e.g. using XInclude; Namespaces
• CPC Class Codes: G06F 40/143 Markup, e.g. Standard Generalized Markup Language [SGML] or Document Type Definition [DTD]
• CPC Class Codes: Y10S 707/99933 Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation

Abstract

A method and system are provided for flexibly sectioning XML documents stored in a relational database system. The method includes obtaining a set of sectioning rules; receiving an XML document that is to be stored in the relational database system; and identifying a storage location for each node in the XML document based on the set of sectioning rules. The sectioning rules can also be used to determine which tables in the relational database should be queried when a query is received, and to determine which tables in the relational database should be updated when a command to update stored XML data is received.

Claims

1. A method of sectioning an XML document having one or more nodes, said method comprising the computer-implemented steps of:

obtaining a set of sectioning rules;

receiving an XML document to be stored in a relational database system; and

based on the set of sectioning rules, identifying storage locations within the relational database system in which to store fragments of the XML document.

2. The method of claim 1 wherein the step of identifying is performed within a database server of the relational database system.

3. The method of claim 1, wherein the XML document does not conform to a defined schema.

4. The method of claim 1, further comprising the step of:

for each node in the XML document that corresponds to a sectioning rule, storing the fragment of the XML document associated with the node in a storage location identified by the corresponding sectioning rule for that node.

5. The method of claim 4, further comprising storing a fragment identifier with each fragment in the identified storage location for the fragment.

6. The method of claim 1, wherein said storage location comprises a table in the relational database system, and a sectioning rule in the set of sectioning rules comprises matching criteria and a table identifier that identifies a table in which a fragment of the XML document that matches the matching criteria is to be stored.

7. The method of claim 6, wherein the matching criteria comprises a path expression.

8. The method of claim 7, wherein matching criteria in a first sectioning rule comprises a first path expression and a first table identifier, and matching criteria in a second sectioning rule comprises a second sectioning rule comprises a second path expression and the first table identifier.

9. The method of claim 6, wherein the step of identifying storage locations comprises:

identifying a rule containing matching criteria that matches a node as a matching rule; and

identifying a storage location for the node as the table associated with the table identifier in the matching rule.

10. The method of claim 9, wherein the step of identifying a rule as a matching rule comprises:

determining that a rule, in the set of rules, matches a node if the matching criteria in the rule includes a path expression that is a superset of the node'"'"'s path.

11. The method of claim 9, wherein the matching criteria comprises a path expression, said method additionally comprising the step of:

initializing a finite state machine to represent path expressions in the set of sectioning rules; and

the step of identifying a rule as a matching rule comprises traversing the finite state machine to identify a rule that includes a path expression that matches the node'"'"'s path.

12. The method of claim 6, wherein the set of rules are ordered, and the step of identifying storage locations comprises the steps of:

(a) setting a first rule in the set of rules as a current rule;

(b) determining whether matching criteria in the current rule matches the node'"'"'s path;

(c) if matching criteria in the current rule does not match the node'"'"'s path, then setting the current node to a next rule in the set of rules, and repeating steps (b) and (c); and

(d) if matching criteria in the current node matches the node'"'"'s path, then identifying the storage location as the table associated with the table identifier in the current rule.

13. The method of claim 1, wherein the received XML document is an updated version of an XML document already stored in the relational database, the method additionally comprising the steps of:

receiving an update command, said command comprised of at least one path-based expression;

based on the sectioning rules, generating a list of storage locations that correspond to the path-based expressions in the update command; and

executing the update command using only the storage locations in the generated list of storage locations.

14. The method of claim 1, wherein the step of obtaining a set of sectioning rules comprises receiving the set of sectioning rules from a user.

15. The method of claim 1, wherein the step of obtaining a set of sectioning rules comprises obtaining the set of sectioning rules from annotations in an XML schema.

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 1.

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 2.

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 3.

23. 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.

24. 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.

25. 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.

26. 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.

27. 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.

28. 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.

29. 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.

30. 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.

31. 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 12.

32. 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 13.

33. 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 14.

34. 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 15.

16. A method of evaluating a query in a relational database system that stores XML data sectioned from XML documents in one or more section tables according to a set of sectioning rules, said method comprising the computer-implemented steps of:

receiving a query, said query comprised of at least one path expression;

generating a list of section table identifiers that identify section tables in the relational database, each said section table identifier corresponding to at least one rule in the set of sectioning rules that matches the at least one path expression; and

evaluating the query using only section tables identified in the generated list.

17. The method of claim 16 wherein the path-based query expression is an XPath query.

18. The method of claim 16 wherein the step of generating a list of section table identifiers comprises the steps of:

identifying at least one matching rule that includes matching criteria that matches the at least one path expression;

identifying a section table for each identified matching rule; and

generating the list comprised of identifiers for each identified section table.

19. The method of claim 18, further comprising the step of:

initializing a finite state machine to represent path expressions in the user-defined sectioning rules; and

wherein the step of identifying at least one matching rule comprises traversing the finite state machine to identify at least one rule that includes matching criteria that matches the at least one path expression.

35. 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 16.

36. 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 17.

37. 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 18.

38. 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 19.