Oracle International Corporation

Oracle International Corpration

Sivasankaran Chandrasekar

Nipun Agarwal

Ravi Murthy

Eric Sedlar

Sam Idicula

Asha Tarachandani

Ashish Thusoo

Thomas Baby

Ning Zhang

Muralidhar Krishnaprasad

Sreedhar Mukkamalla

Bhushan Khaladkar

Anh-Tuan Tran

James W Warner

Balasubramanyam Sthanikam

Viswanathan Krishnamurthy

Abhyudaya Agrawal

Vijay Medi

Fei Ge

Nitin Kumar Gupta

Zhen Hua Liu

Anand Manikutty

Man-Hay Tam

Ali Maleki Tabar

Subramanian Muralidhar

Lik Wong

Namit Jain

Nimar Singh Arora

Sabina Petride

Geeta Arora

Syam Sundar Pannala

Sundeep Abraham

Olga Peschansky

K Karun

Neema Jalali

Dmitry Lenkov

Kwok Lun Alex Yiu

Sanket Malde

Reema Koo

Anjana Manian

Ellen Batbouta

A method and apparatus for managing hierarchical relationships in a relational database system is provided. An 'orderkey' data type, which is native within a relational database system, is disclosed. The orderkey type is designed to contain values that represent the position of an entity relative to the positions of other entities within a hierarchy. Such values represent hierarchical relationships between those entities. Values that are of the orderkey type have properties that allow hierarchy-oriented functions to be performed in an especially efficient manner. Database functions, which operate on and/or produce values that are of the orderkey type, are also disclosed. Such functions can be placed within SQL statements that a database server executes, for example. In response to executing SQL statements that contain such functions, the database server performs hierarchy-oriented operations in a highly efficient manner.

Efficient mechanism for managing hierarchical relationships in a relational database system

Techniques are provided for encoding/decoding binary XML data in a client program before sending/receiving the XML to/from a database server. By encoding the binary XML at the client, the overhead of parsing the XML text is avoided by the database server, thus improving database server scalability. Also, the XML data is sent by the server to the client in the binary form, and the binary format is decoded by the client program to perform the necessary operations.

Client processing for binary XML in a database system

A database system may utilize XML schema information to increase the efficiency of an XPath streaming evaluation. The database system may access XML schema or translation information during the evaluation of an element, attribute, or value in an XML data source. Based on the XML schema or translation information, the database system may determine matches to an XPath expression without decoding any binary-encoded data in the XML data source. Also, based on the XML schema information, the database may selectively skip or evaluate portions of the XML data source depending on whether those portions are defined in the XML schema so as to possibly contain a match to one or more unmatched steps in the XPath expression. XML schema information may be compiled into a compiled representation of the XPath expression for additional efficiencies.

Efficient streaming evaluation of XPaths on binary-encoded XML schema-based documents

A database server exploits the power of compression and a form of storing relational data referred to as column-major format, to store XML documents in shredded form. The column values that are to be stored for shredded XML documents are separately analyzed for a XML document to determine whether to store a particular column in column-major format or row-major format, and what compression technique to use, if any.

Technique for compressing XML indexes

A database server determines, on an element-level of granularity, what form of VARRAY storage to map collections of elements defined by a XML schema. A collection element may be mapped to an in-line VARRAY or an out-of-line VARRAY. The determination may based on a variety of factors, including the database type mapped to the collection element, database limitations that limit the form storage for certain database types, and annotations ('mapping annotations') embedded within that XML schema that specifying a database type for database representation of a collection element or a form of VARRAY storage.

Flexible storage of XML collections within an object-relational database

A mechanism is provided for detecting and disregarding application specific nodes contained in shared XML documents. The techniques described involve determining one or more application specific nodes within XML documents and performing path expression evaluations of the XML documents as if the nodes are not present. In one embodiment, a mechanism is provided by which a user may specify the criterion that determine which subset of node in XML documents are to be ignored from path expression evaluations and evaluating a query that specifies a path operation based on a path and ignoring said identified nodes when evaluating said path operation.

Isolation for applications working on shared XML data

To improve performance of performing XML operations on an XML document in by a client tier, the client generates an index that indexes the nodes of an XML document. The index may be generated, for example, by and during parsing of the XML document. The index contains similar structures to those maintained by a database server to perform XML operations on collections of XML documents. In lieu of parsing XML document to generate an index, the client may generate indexes based on data retrieved from the indexes at the database server.

Document level indexes for efficient processing in multiple tiers of a computer system

The approaches described herein provide an efficient way to process certain kinds of queries that retrieve XML data stored in an object-relational database. An XML query may include a predicate condition that joins two row sources. One or both of the row sources required for predicate evaluation may be path-based; that is, consume and produce rows of XMLType data. Such a path-based row source may be modified to use the predicate condition to filter the rows it generates so that only rows satisfying the predicate condition need to be further processed. A small cache structure introduced into the path-based row source may be used to optimize the evaluation of the predicate row. Once populated with row data, the cache structure may be reorganized to optimize the performance of predicate evaluation.

Cache-based predicate handling for queries on XML data using uncorrelated path-based row sources

A method and apparatus for efficiently maintaining XML index structures in a database system is provided. Instead of immediately synchronizing the XML index structures for every change submitted to the database, the changes are stored in a PENDING table. The XML index structures are periodically synchronized, based on certain criteria or at a user's discretion. Between synchronizations, the XML index structures may be in stale mode or current mode. If in stale mode, a request to access indexed information will use the XML index structures to find the desired indexed information without checking the PENDING table. If in current mode, a request to access indexed information will search the XML index structures and also check the PENDING table to determine 1) whether the indexed information has been updated or deleted, and 2) whether information relevant to the request has been inserted or updated.

Mechanism for efficient maintenance of XML index structures in a database system

A database system automatically detects a cyclic construct in a XML schema, determines a database representation for the cyclic construct, and maps the XML schema and elements involved in the cyclic construct to the database representation.

Managing cyclic constructs of XML schema in a rdbms

One may increase the efficiency of an XML event-generating process by reducing the number of requests to allocate or deallocate system memory. Such reduction may occur as the result of pre-allocating a memory chunk of sufficient size to contain all of the memory buffers required by a particular event-generating process. Instead of allocating new memory chunks for new memory buffers, an application may store any required buffers within the pre-allocated memory chunk. A sufficient memory size may be estimated by performing the event-generating process on a training set of XML documents. Also, an application may re-use buffers during the process or between different iterations of the process, thus avoiding the need to deallocate and reallocate memory that is essentially being used for the same purpose.

Techniques for more efficient generation of XML events from XML data sources

A mechanism is provided for detecting and disregarding application specific nodes contained in shared XML documents. The techniques described involve determining one or more application specific nodes within XML documents and performing path expression evaluations of the XML documents as if the nodes are not present. In one embodiment, a mechanism is provided by which a user may specify the criterion that determines which subset of nodes in XML documents are to be ignored from path expression evaluations. A query that specifies a path operation based on a path is evaluated ignoring said identified nodes when evaluating said path operation.

A modular repository is described, where operational features may be implemented without the need to scan every resource included in the modular repository. A modular repository includes a dedicated set of database objects containing all information needed to access the resources in the repository. For example, the database objects of a modular repository may include those user identifier mappings and ACL mappings, etc., to which metadata in the modular repository refers. A database system may also include a mechanism through which a modular repository may be mounted under a subdirectory of a common directory in the database system. The resources of a modular repository that are mounted under the common directory may be accessed through the common directory. Further, a client may query the resources of any modular repository mounted under the common directory by making the federated repository, represented by the common directory, the context of the query.

Operationally complete hierarchical repository in a relational database

Techniques are provided for efficiently extracting scalar values from binary-encoded XML data. Node information is stored in association with binary-encoded XML data to indicate whether one or more nodes of an XML document are simple or complex. A node is simple if the node has no child elements and no attributes. The node information of a particular node is used to determine whether a particular node, identified in a query, is simple or complex. If the particular node is simple, then the scalar value of the particular node is identified without performing any operations other than possibly converting the scalar value to a non-binary-encoded format or converting the scalar value to a value of a different data type.

Fast extraction of scalar values from binary encoded XML

In a database system, names and namespace of XML nodes are computed from path ids. The path ids are constructed from tokens, each of which represents a particular name or namespace-name pair.

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Palo Alto, CA, United States of America

Sivasankaran Chandrasekar