Oracle International Corporation

Fei Ge

Nipun Agarwal

Ravi Murthy

Eric Sedlar

Sivasankaran Chandrasekar

Namit Jain

Subramanian Muralidhar

Sam Idicula

Andrew Witkowski

Hakan Jakobsson

Ari Wolfe Mozes

A mechanism is used to improve the efficiency of performing resource-to-path resolution. A hierarchical link structure contains entries and/or records ('link entries') that each defines a parent-child link within an information hierarchy. A certain linking entry may have data that refers to another link entry representing a link to the parent&#x2014;a link in which the parent is a child. This data allows resource-to-path resolutions to be performed more efficiently.

Efficient processing of path related operations on data organized hierarchically in an RDBMS

Cost-based optimizer functionality for an XML database repository provides means for optimizing the execution of database queries that access XML resources in the database repository. Statistics about XML resources that are stored in the database repository are gathered, stored and utilized by a query optimizer to compute computational costs associated with each of multiple methods of accessing particular XML resources requested in a database query. Hence, the optimizer is able to select the most efficient query execution plan based on the costs of possible access paths. In one embodiment, specific statistics about the hierarchical structure of XML resources stored in the XML database repository are gathered, stored in a relational table in the database management system, and used to compute the selectivity of query predicates and the index cost associated with traversing one or more indexes to access requested XML resources.

Cost-based optimizer for an XML data repository within a database

A method and apparatus for processing path-based database operations is provided. According to one aspect, a 'parent row ID' column is added to a directory links table. For each row in the table, the value of the 'parent row ID' column indicates the row ID, in the table, of the node that is that row's node's parent in the file hierarchy. To determine whether a particular node is within a specified path of the file hierarchy, the particular node's pathname is derived by visiting child-to-parent links indicated in the table and prepending, to the front of a pathname being constructed for the particular node, node names indicated in the visited rows. Each parent node's row in the directory links table is located using the &#x201c;parent row ID&#x201d; column of the child node's row. The resulting pathname is compared with the specified path to determine whether the particular node exists therein.

Processing path-based database operations

Techniques and systems are provided for efficiently managing hierarchical relational data stored in object-relational database system by extending the syntax of the database language supported by the database system (e.g. SQL) to incorporate several new 'hierarchical' operators. These operators are evaluated based on the hierarchical relationship defined for hierarchical relational data. The operators maybe incorporated in SQL queries along with relational operators.

Operators for accessing hierarchical data in a relational system

Techniques for managing hierarchical data include managing a link table in a relational database. The hierarchical data includes data about a hierarchy of nodes related by multiple links. The link table includes first information, second information and link information, for each link. First information indicates a first node in the hierarchical data. Second information indicates a second node that is associated with the first node by the link. Link information indicates values for link attributes of the link between the first node and the second node, and does not indicate a value for any attribute of the first node alone or any attribute of the second node alone. The techniques support directing a single SQL statement to a path database object, constructed based on the link table, in order to obtain paths that satisfy a search on link attributes.

Techniques for managing hierarchical data with link attributes in a relational database

Techniques for processing, in a database management system, a query referencing a plurality of tables of a database include determining whether a join should be performed between a first table and a second table. The determination is based on a particular set of one or more columns of the second table referenced in the query and a join index on the first table for an index key column from the second table. If it is determined that the join should not be performed, the query is processed without performing the join between the first table and the second table. By avoiding one or more joins, substantial savings in the consumption of computational resources are achieved.

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Palo Alto, CA, United States of America

Fei Ge