Indexing Mechanism for Efficient Node-Aware Full-Text Search Over XML

• US 20100169354A1
• Filed: 12/30/2008
• Published: 07/01/2010
• Est. Priority Date: 12/30/2008
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Baby, Thomas, Liu, Zhen Hua, Lin, Wesley
• Granted Patent: US 8,219,563 B2
• Time in Patent Office: Days
• US Class Current: 707/765
• CPC Class Codes: G06F 16/81 Indexing, e.g. XML tags; Data structures therefor; Storage structures

Abstract

Techniques are provided for searching within a collection of XML documents. A relational table in an XML index stores an entry for each node of a set of nodes in the collection. Each entry of the relational table stores an order key and a path identifier along with the atomized value of the node. An index on the atomized value provides a mechanism to perform a node-aware full-text search. Instead of storing the atomized value in the table, a virtual column may be created to represent, for each node, the atomized value of the node. Alternately, each entry of the relational table stores an order key and a path identifier along with, for simple nodes, the atomized value, and for complex nodes, a null value. For a complex node with a descendant text node, a separate entry is stored for the descendant text node in the relational table.

Claims

1. A computer-implemented method comprising:

storing a table that stores data for a plurality of nodes in a collection of XML documents, the table comprising an entry for each node of the plurality of nodes, the entry of each node comprising;

path data that specifies a path, through the structure of the XML document, to the node; and

an atomized value of the node;

storing a full-text index of the atomized values stored in the entries of the table.

2. The computer-implemented method of claim 1, wherein said atomized value is formed by concatenating a text value of said node with text values of descendant nodes.

3. The computer-implemented method of claim 1, wherein the atomized values are stored in a column of said table, said column being of a character large object type.

4. The computer-implemented method of claim 1, further comprising:

receiving a query that requires a text search of the collection of XML documents; and

rewriting said query to produce a rewritten query, wherein said rewritten query causes using said full-text index to compute said rewritten query.

5. The computer-implemented method of claim 1, further comprising:

receiving a query that specifies certain criteria, said criteria comprising;

one or more criteria for text contained in a node; and

one or more criteria for a path of a node;

rewriting said query to produce a rewritten query, wherein said rewritten query causes using full-text index and said table to compute which one or more nodes of said plurality of nodes satisfy said criteria.

6. A computer-implemented method comprising:

receiving a query that requests data from a collection of XML documents;

wherein said collection of XML documents comprises a plurality of nodes;

wherein a certain index comprises a table that comprises a plurality of rows, each row of said plurality of rows corresponding to a node of said plurality of nodes;

wherein each row of said plurality of rows includes;

path data that specifies a path, through the structure of the XML document, to the node, said path identifier being stored in a path data column of said table, and

an atomized value of the node, said atomized value being contained in a virtual column of said table;

wherein said certain index of said collection of XML documents comprises a full-text index, said virtual column being indexed by said full-text index;

rewriting said query to produce a rewritten query, wherein said rewritten query causes using said full-text index to compute said rewritten query.

7. The computer-implemented method of claim 6, wherein said atomized value of said virtual column is evaluated by concatenating a text value of said node with text values of descendant nodes.

8. The computer-implemented method of claim 7, wherein said text value of said node is obtained from said value column of said table.

9. A computer-implemented method comprising:

receiving a query that requests data from a collection of XML documents;

wherein said collection of XML documents comprises a plurality of nodes;

wherein a certain index comprises a table that stores data for a plurality of nodes in a collection of XML documents, the table comprising a virtual column that contains, for each node, an atomized value of the node;

wherein said virtual column is indexed by a full-text index;

rewriting said query to produce a rewritten query, wherein said rewritten query causes using said full-text index to compute said rewritten query.

10. The computer-implemented method of claim 9, wherein said atomized value of said virtual column is evaluated by concatenating a text value of said node with text values of descendant nodes.

11. The computer-implemented method of claim 10, wherein said text value of said node is obtained from a value column of said table.