Index for accessing XML data

• US 20050228792A1
• Filed: 07/02/2004
• 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, Murthy, Ravi, Agarwal, Nipun, Tran, Anh-Tuan, Chandrasekaran, Sivasankaran, Mukkamalla, Sreedhar
• Granted Patent: US 7,499,915 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

Techniques are provided for indexing XML documents. According to one embodiment, a PATH table created for storing one row for each indexed node of the XML documents. The PATH table row for a node includes (1) information for locating the XML document that contains the node, (2) information that identifies the path of the node, and (3) information that identifies the position of the node within the hierarchical structure of the XML document that contains the node. If the node is associated with the value, then the PATH table row for the node may also include the value. Use of the PATH table to answer XPath queries is facilitated by secondary indexes.

Claims

1. A method for accessing information from XML documents, the method comprising:

identifying, within the XML documents, a set of nodes to be indexed;

for each node in the set of nodes to be indexed, storing, in an index, an entry for the node, wherein the entry for a given node includes location data for locating XML content associated with the given node, and at least one of;

(a) hierarchical data that indicates a hierarchical position of the given node within the XML document that contains the given node; and

(b) path data that corresponds to a path, through the structure of the XML document that contains the given node, to the given node; and

using the index to locate information within the XML documents in response to requests for information from the XML documents.

2. The method of claim 1 wherein the index is implemented as a relational table, and the step of storing an entry for each node is performed by storing a row, within the relational table, for each node in the set of nodes.

3. The method of claim 1 wherein the index stores values associated with one or more nodes in the set of nodes.

4. The method of claim 3 wherein the values stored in said index include values of a plurality of datatypes, and the method further comprises the step of building a secondary index for each of two or more datatypes of said plurality of datatypes.

5. The method of claim 1 wherein the location data for a given node includes first data for locating an XML document, and second data for locating, within the XML document, information associated with the given node.

6. The method of claim 1 wherein:

the entry for a given node includes hierarchical data that indicates a hierarchical position of the given node within the XML document that contains the given node; and

the method further comprises building a secondary index for accessing entries in said index based on said hierarchical data.

7. The method of claim 1 wherein:

the entry for a given node includes path data that corresponds to a path, through the structure of the XML document that contains the given node, to the given node; and

the method further comprises building a secondary index for accessing entries in said index based on said path data.

8. The method of claim 1 further comprising building a secondary index for accessing an entry, in said index, for a parent node based on hierarchy information associated with a child node of said parent node.

9. The method of claim 1 wherein the step of identifying a set of nodes to be indexed includes the steps of:

receiving rules for determining which paths should be indexed;

determining the paths associated with nodes in an XML document that is to be indexed; and

identifying which nodes are to be indexed based on (a) the rules for determining which paths should be indexed, and (b) the paths associated with the nodes in the XML document that is to be indexed.

10. The method of claim 9 wherein the rules explicitly identify paths that are to be included in the index.

11. The method of claim 9 wherein the rules explicitly identify paths that are to be excluded from the index.

12. The method of claim 4 further comprising receiving user data that indicates the datatypes for which secondary value indexes are to be built.

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 1.

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 2.

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 3.

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 4.

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 5.

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 6.

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 7.

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 8.

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 9.

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 10.

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 11.

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 12.