Ravi Murthy

Oracle8i-the XML enabled data management system

XML is here as the Internet standard for information exchange among e-businesses and applications. With its dramatic adoption and its ability to model structured, unstructured and semi-structured data, XML has the potential of becoming the data model for Internet data. In recent years, Oracle has evolved its DBMS to support complex, structured, and un-structured data. Oracle has now extended that technology to enable the storage and querying of XML data by evolving its DBMS to an XML enabled DBMS, Oracle8i. We present Oracles XML-enabling database technology. In particular, we discuss how XML data can be stored, managed and queried in the Oracle8i database.

Xml schemas in Oracle XML DB

The W3C XML Scheme language is becomimg increasingly popular for expressing the data model for XML documents. It is a powerful language that incorporates both strutural and datatype modeling features. There are many benefits to storing XML Schema compliant data in a database system, including better queryability, optimied updates and stronger validation. However, the fidelity of the XML document cannot be sacrificed. Thus, the fundamental problem facing database implementers is: how can XML Schemes be mapped to relational (and object-relational) database without losing schema semantics or data-fidelity? In this paper, we present the Oracle XML DB solution for a flexible mapping of XML Schemas to object-relational database. It preserves document fidelity, including ordering, namespaces, comments, processing instructions etc., and handles all the XML Schema semantics including cyclic definitions, dervations (extension and restriction), and wildcards. We also discuss various query and update optimiations that involve rewriting XPath operations to directly operate on the underlying relational data.

Extensible indexing: a framework for integrating domain-specific indexing schemes into Oracle8i

Extensible indexing is a SQL-based framework that allows users to define domain-specific indexing schemes, and integrate them into the Oracle8i server. Users register a new indexing scheme, the set of related operators, and additional properties through SQL data definition language extensions. The implementation for an indexing scheme is provided as a set of Oracle Data Cartridge Interface (ODCIIndex) routines for index-definition, index-maintenance, and index-scan operations. An index created using the new indexing scheme, referred to as domain index, behaves and performs analogous to those built natively by the database system. The Oracle8i server implicitly invokes user-supplied index implementation code when domain index operations are performed, and executes user-supplied index scan routines for efficient evaluation of domain-specific operators. This paper provides an overview of the framework and describes the steps needed to implement an indexing scheme. The paper also presents a case study of Oracle Cartridges (intermedia text, spatial, and visual information retrieval), and Daylight (Chemical compound searching) Cartridge, which have implemented new indexing schemes using this framework and discusses the benefits and limitations.

Towards an enterprise XML architecture

XML is being increasingly used in diverse domains ranging from data and application integration to content management. Oracle provides an enterprise wide platform for managing all types of XML content. Within the Oracle database and the application server, the XML content can be efficiently stored using a variety of storage and indexing methods and it can be processed using multiple standard languages within different programmatic environments.

A Decade of XML Data Management: An Industrial Experience Report from Oracle

XML and its related technologies have now been in use for almost a decade. There has been considerable amount of effort both from research and industry focusing on XML, XQuery/XPath, XSLT and SQL/XML processing in the database. Many research prototypes and industrial products have been built to satisfy the XML use cases. This paper reviews several use cases where XML databases are leveraged to build real-world XML applications. We discuss the lessons learnt in supporting both data-centric and document-centric XMLDB applications within a single database system and the need for the implementation of different XML storage, index and query optimisation techniques for different XML use cases. We show the value of managing XML in databases, the current challenges and improvements that will hopefully promote future research directions. This paper also provides a timely checkpoint of XML data management from industrial perspective with experience of developing and supporting Oracle XML products.

Flexible and efficient access control in oracle

A single model for access control across the database and application server tiers is crucial to ensure consistent secure access to data in all the tiers. In this paper, we present the common model for access control within Oracle database and application tiers which is based on the standard WebDAV ACLs (Access Control Lists). Further, we discuss the flexible mechanisms for defining ACLs and associating them with data and various optimization techniques for efficiently evaluating ACLs in large scale enterprise applications.

Supporting ancillary values from user defined functions in Oracle

Most commercial SQL database systems support user-defined functions that can be used in WHERE clause filters, SELECT list items, or in sorting/grouping clauses. Often, user-defined functions are used as inexact search filters and then the filtered rows are sorted by a relevance measure. This is commonplace in Web search engines, multimedia, and personalization applications. We refer to the values, such as relevance measure, associated with the filtered rows as ancillary values, and address the problem of efficiently and expressively supporting queries involving them in Oracle. In our approach, the filtering operator is designated as the primary operator, and the associated ancillary values are modeled by additional operators that are declared to be ancillary to the primary operator. An ancillary operator can represent any auxiliary value for the filtered rows, including relevance values (e.g. a score which describes how well a document matches the text search query) and additional properties (e.g. the nature of spatial relationship for objects that overlap a given region). The query execution is optimized by allowing the primary and ancillary operator invocations to share computations via a shared context. Also, queries involving ancillary values can exploit user defined indexes and their capability to return results in the order of ancillary values. We present the key concepts, describes our implementation scheme and optimization techniques, and discusses alternative approaches for supporting ancillary values. Finally, we provide an experimental study that illustrates the scalability and effectiveness of our approach.