Providing XML cursor support on an XML repository built on top of a relational database system

A method for providing multi-dimensional XML cursor functionality for a query of XML data stored in a relational database comprising steps of:

• a. receiving a query issued over an XML document;
• b. translating said query issued over an XML document into a top-level SQL query returning only root nodes in a result,
• c. generating one or more additional SQL queries,
• d. choosing an SQL query or SQL queries to send to said relational database via an XML cursor, said XML cursor constructed via an outer union approach,
• e. executing said SQL query or SQL queries, and
• f. navigating a dataset resulting from execution of said SQL queries, said navigating step comprising:
• choosing and executing a single SQL query to said relational database with resulting dataset;
• navigating to a previous or next tuple in said resulting dataset and returning said next or previous tuple if the previous or next node is requested by a navigation component;
• traversing through previous tuples in said resulting dataset until a parent, previous sibling, or previous tree root tuple is found, and navigating to a desired tuple directly if distance information is available, and returning said tuple if a parent, previous sibling, or previous tree root node is requested by said navigation component;
• or traversing through next tuples in said resulting dataset until a child, next sibling, or next tree root tuple is found, or going to a desired tuple directly if distance information is available, and returning said tuple if a child, next sibling, or next tree root node is requested by said navigation component.

A system for multi-dimensional navigation of an XML document comprising:

• a. an XML cursor manipulated by a user, said XML cursor implemented via a hybrid approach, said hybrid approach has steps comprising:
• choosing a query generated for a root node, sending it to and executing it in said relational database if a previous tree root or next tree root node is selected by XML query cursor position;
• choosing a parameterized SQL query generated for current element type if a previous sibling or next sibling node is also selected by XML query cursor position;
• choosing one or more parameterized SQL queries, depending on the element type of a selected node, sending one or more queries to and executing one or more queries in said relational database if necessary, if a previous or next node is requested by XML query cursor position, and navigating to a previous or next tuple of dataset result generated by said execution of selected SQL queries and returning said previous or next tuple, and
• b. an XML schema over which said XML cursor navigates,
• c. a relational database for storing tuples of XML data corresponding to said XML document, and
• d. a relational database cursor for traversing said tuples of XML data.

A method for providing multi-dimensional XML cursor functionality for a query of XML data stored in a relational database comprising steps of:

• a. receiving a query issued over an XML document;
• b. translating said query issued over an XML document into a top-level SQL query that will return only root nodes in a result,
• c. generating one or more additional SQL queries,
• d. choosing an SQL query or SQL queries to send to said relational database via an XML cursor, said XML cursor constructed via an hybrid approach,
• e. executing said SQL query or SQL queries, and
• f. navigating a dataset resulting from execution of said SQL queries, said navigating step comprising:
• choosing said top-level SQL query generated for a root node, sending it to and executing it in said relational database if a previous tree root or next tree root node is requested by said navigation component;
• choosing said parameterized SQL query generated for current element type if a previous sibling or next sibling node is requested by navigation component, choosing one or more parameterized SQL queries, depending on the element type of a requested node, sending one or more queries to and executing one or more queries in said relational database if necessary, if a previous or next node is requested by navigation component;
• and, navigating to a previous or next tuple of dataset result generated by said execution of chosen parameterized or top-level SQL queries and returning said previous or next tuple.