Oracle International Corporation

Balasubramanyam Sthanikam

Nipun Agarwal

Sam Idicula

Sivasankaran Chandrasekar

Ravi Murthy

Zhen Hua Liu

Hui Joe Chang

Muthu Olagappan

Lawrence J Ellison

Ning Zhang

Jay Rossiter

Ramkumar Venkataraman

Jane Xin Chen

Venkat Malla

Yuanjiang Ou

Pari Bhaduri

Vijay Medi

David Stowell

Niloy Banerjee

Thivakaram Prakash Sivakumar

John John E So

Dimitris Nakos

Lalitha Ganti

C Gregory Doherty

Srinivas Maturi

Bala Kumaresan

Sivasanakan Chandrasekar

Harish Rawat

Joseph Therrattil Koonen

A method for storing XML documents a hybrid navigation/streaming format is provided to allow efficient storage and processing of queries on the XML data that provides the benefits of both navigation and streaming and ameliorates the disadvantages of each. Each XML document to be stored is independently analyzed to determine a combination of navigable and streamable storage format that optimizes the processing of the data for anticipated access patterns.

Hybrid binary XML storage model for efficient XML processing

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

The approaches described herein provide an efficient way to process certain kinds of queries that update XML data stored in an object-relational database. A query may include an XML query expression that conforms to a language for querying XML documents. A technique first determines whether the query contains an XML updating expression, and in response rewrites the query to comprise one or more path-based query operators that specify operations for updating XML data. The query may then be further rewritten to comprise one or more storage format specific query operators based on the particular database storage format associated with the XML data specified in the query. The rewritten query operators are used to generate a query execution plan that provides for several query execution optimizations.

Techniques for efficiently supporting XQuery update facility in SQL/XML

A technique for differencing XML documents is provided. An edit graph is generated for computing the cost of possible edits that may be applied to a first XML document in order to generate a second XML document. A hash value is assigned to nodes included in the axes of the edit graph, where one axis includes nodes in the first XML document and the other axis includes nodes in the second XML document. The hash value may be generated based on a particular node's name and attributes, and the hash value of the name and attributes of each child node of the particular node. A technique for patching an XML document is also provided. Events are generated for each node in the input document and for at least one operation specified in the edit script. The edit script is applied to the input document by performing one or more operations specified in the operation events on one or more node events.

Efficient evaluation for diff of XML documents

The approaches described herein provide an efficient way for a database server to process certain kinds of queries that require the evaluation of an aggregation function over XML data stored in an object-relational database. An aggregation function takes multiple inputs and generates a single output. A database server first determines whether the query qualifies for this particular kind of optimization, then creates a query execution plan that specifies the use of an enhanced path-based row source, eliminating the need for a second path-based row source for computing the aggregation function. The enhanced path-based row source specified in the query execution plan computes an aggregation function and stores the result of that function computation in a column of each row. The XPath evaluation results that are the individual inputs to the aggregation function are only stored temporarily until they are used to compute the aggregation function.

Efficient way to evaluate aggregations on XML data using path-based row sources

The approaches described herein provide an efficient way to process certain kinds of queries that retrieve XML data stored in an object-relational database. A technique determines whether a query comprises a plurality of iteration expressions that exhibit a particular relationship to one another, and if so, re-writes the query and produces an optimized query execution plan. The query execution plan specifies an XPath-based row source with caching enabled. A very small cache structure is used, and reference locators are stored in the cache that point into binary-encoded data rather than copying XMLType data into the cache. Row data may be cached on the first use of the path-based row source and re-used in subsequent requests for rows. Once there is a subsequent request for rows from the optimized path-based row source, the cache may be reorganized to efficiently produce the rows of the row source.

Efficient way to evaluate uncorrelated path-based row sources with XML storage

The approaches described herein provide an efficient way for a database server to process certain kinds of queries over XML data stored in an object-relational database that require the evaluation of a predicate expression with one or more path-based operands. A predicate expression part of a XQuery or SQL WHERE clause that returns a boolean value. A database server first determines whether the query qualifies for this particular kind of optimization, then rewrites the query using an enhanced query operator syntax for specifying the predicate expression to be evaluated. The enhanced query operator subsumes the work of a second path-based query operator, resulting in the suppression of the WHERE EXISTS subquery. The rewritten query operator is used to generate a query execution plan that provides for several query execution optimizations.

Query optimization by specifying path-based predicate evaluation in a path-based query operator

Techniques are provided for ensuring lexical fidelity when an XML document is stored in a binary format. Operations, on the XML data, that would cause the loss of lexical fidelity between the original XML document and the binary-encoded version of the XML document are not performed. Such operations include the removal of unnecessary whitespace characters, certain data type conversions, CRLF normalization, the 'collapsing' of two-tag empty elements into a single tag empty element, and the replacing of entity references or numeric character references with another value. An XML schema, to which the XML document conforms, may indicate that the XML document is to be stored in a lexical fidelity mode. Additionally, or alternatively, the database statement that (when executed) causes the XML document to be stored in a binary format may so indicate.

Document fidelity with binary XML storage

Streaming XML patch

A mechanism is provided for improving the performance of particular database queries operating on a view comprising binary-encoded XML. A determination is made about whether a XML index is available to improve the computation of XPath data before deriving an optimized execution plan for a particular query. When a XML index is not available to help expedite the computation of binary-encoded XML, then deferring the computation of the XPath data until after the view merge stage avoids unnecessary computation of XPaths that are part of the view but not needed for the particular query.

Mechanism for deferred rewrite of multiple XPath evaluations over binary XML

Techniques are described for preserving the original insignificant white space of XML data. The techniques may be used in combination with compact XML data storage formats, such as binary XML, to preserve the insignificant white space without requiring as much storage space as uncompressed formats. White space opcodes/operand pairs are described for representing white space characters and white space patterns. The white space opcode/operand pairs represent the white space in binary XML, are use to generate the original white space when the binary XML is decoded back to textual XML data.

Encoding insignificant whitespace of XML data

A database system that incorporates numerous features that reduce the total cost of maintaining the database system is provided. That database system includes a database appliance that executes a database server on a platform that includes a special purpose operating system specifically tailored to the services required by the database server. The database appliance configures itself by detecting the environment in which it resides and setting operational parameters based on the detected environment. The configuration metadata of all components of the system are stored in a centralized repository which itself may reside external to the system. Both the database server configuration and the operating system configuration are managed by a remotely located integrated management console, which interacts with and configures the system at the database system level, the operating system level and, optionally, at the hardware subsystem level. Backup management may also be performed remotely. The remote components, such as the integrated management console, the backup server, and the configuration repository, may communicate with the system through a wide area network, such as the Internet, or directly through a dial-up connection.

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Foster City, CA, United States of America

Balasubramanyam Sthanikam