A method and system are provided for allowing users to register XML schemas in a database system. The database system determines, based on a registered XML schema, how to store within the database system XML documents that conform to the XML schema. This determination involves mapping constructs defined in the XML schema to constructs supported by the database system. Such constructs may include datatypes, hierarchical relationship between elements, constraints, inheritances, etc. Once the mapping has been determined, it is stored and used by the database system to determine how to store subsequently received XML documents that conform to the registered XML schema.

Mechanism for mapping XML schemas to object-relational database systems

Two computers are respectively programmed to generate descriptions of database objects (such as tables) in a first database, and compare the generated descriptions to corresponding schema objects in a second database. Objects in the second database are changed to conform to the first database if differences are found during comparison. The just-described differences in objects may arise due to changes being made to a software program that uses data contained in the objects.

Method(s) for updating database object metadata

In response to the provision of a collection of semi-structured data (or its schema), a mapper generates a structured organization to store the collection of semi-structured data. The mapper further collaterally generates a description of how the semi-structured data are stored under the structured organization. In one embodiment, normalized relational tables are used for the structured organization. In alternate embodiments, non-normalized relational tables or other structured organization may also be used. The reverse, that is, the creation of a semistructured data organization for a collection of structured data may also be performed.

Method and apparatus for storing semi-structured data in a structured manner

Techniques for extensible stylesheet designs using meta-tag and/or associated meta-tag Information are described. To generate a proper stylesheet (e.g., an XSL or XSLT file) from a source file (e.g., an XML file), all meta-tag and/or associated meta-tag Information are differentiated by attaching respectively unique identifiers to those that are otherwise identical. To facilitate user required operations on certain data in the source file, a document source path for the data is identified and inserted with one or more operators thus to form document source path information. The differentiated meta-tag and/or associated meta-tag Information and source path information are relied upon to generate one or more stylesheets. In addition, a user graphic interface environment is provided to facilitate the designes of the stylesheets.

Extensible stylesheet designs using meta-tag and/or associated meta-tag information

An interface and a method is provided for permitting a user to explore a collection of data. The data collection provides nodes as structural elements, and references which are assigned to nodes and hold the address of another node. Multiple references can be assigned to each node, thus guiding a user of the system to multiple other nodes, and multiple references can hold the same address, so that multiple nodes can have references pointing to the same node. The interface allows visualizing the network created by the interconnection of the nodes on a display region. The interface also allows the user to intuitively navigate along the references in both directions of the references, so that the user can explore which nodes are referenced by a certain node, and also by which nodes a certain node is referenced. Electronic documents can be assigned to each node, and the interface allows these documents to be displayed either directly in a reserved display region of the interface, or by launching a matching application on the user's computer.

Interface and method for exploring a collection of data

A system and a method are provided for generating (28) a schema (22) for a relational database corresponding to a document having a document-type definition (18) and data complying with the document-type definition (18). The document-type definition (18) has content particles representative of the structure of the document data including one or more of the following content particles: elements, attributes of elements, nesting relationships between elements, grouping relationships between elements, schema (22) ordering indicators, existence indicators, occurrence indicators and element ID referencing indicators. The system and method described herein also contemplates loading the data into the relational database in a manner consistent with the relational schema (22). Metadata is extracting from the document-type definition (18) representative of the document-type definition (18). The schema (22) for the relational database is generated from the metadata, wherein at least one table is thereby defined in the relational database corresponding to at least one content particle of the document-type definition (18) via the metadata (34). The data is then loaded into the at least one table of the relational database according to the relational schema (22) in a manner driven by the metadata (34).

System and method for automatic loading of an xml document defined by a document-type definition into a relational database including the generation of a relational schema therefor

A system and a method for synchronizing and updating a relational database with supplemental data in which the relational database has a set of tables defined by a relational schema. The supplemental data preferably comprises data in a tagged format having a document-type definition representative of the relational schema and is represented in a document object. The system and method preferably ensure record-by-record updating and synchronization of the relational database with the at least one proposed data update by receiving at least one proposed data update from a source external to the relational database; and propagating the received at least one proposed data update into the relational database. In this matter, the compliance with both the relational database relational schema and the tagged data document type definition is ensured without requiring reloading existing data in the relational database.

System and method for synchronizing and/or updating an existing relational database with supplemental XML data

XQuery, the defacto XML query language, is typically composed of highly nested expressions. Iterative execution of such expressions tends to be intuitive but inefficient. Instead, decorrelation of nested XQuery expressions opens up the opportunity for significant query optimization. Although several algorithms have been proposed to optimize nested XQueries, these works pay little attention to the ordered semantics of XQuery expressions. The appropriate extension of decorrelation to XQuery with multiple level orderby clauses and other order sensitive functions hence represents an important and non-trivial task. We propose an algebraic rewriting technique of nested XQuery expressions containing explicit orderby clauses. The proposed work successfully addresses the challenges caused by the hierarchical nature and the ordered semantics of XQuery expressions. Using a running example, our decorrelation algorithm is illustrated. Further, we show the performance gain achievable by our approach via an experimental study.

Algebraic XQuery Decorrelation with Order Sensitive Operations

n recent years, the number of digital informa-tion storage and retrieval systems has increasedimmensely. These information sources are gen-erally interconnected via some network, andhence the task of integrating data from differ-ent sources to serve it up to users is an increas-ingly important one [10]. Applications thatcould benefit from this wealth of digital informationare thus experiencing a pressing need for suitable inte-gration tools that allow them to make effective use ofsuch distributed and diverse data sets. In contrast to the on-demand approach to informa-tion integration, the approach of tailored informationrepository construction, commonly referred to as datawarehousing, is characterized by the following proper-ties: • At setup time, relevant information is extractedfrom different information sources on the network,transformed and cleaned as necessary, merged withinformation from other sources, and then loadedinto a centralized data store—the data warehouse. • During query processing time, queries posedagainst the system are directly evaluated against thedata warehouse without further interaction with theoriginal sources. • During operation time, modifications of the sourcesare filtered for relevance and are then propagated insome manner to upgrade the data warehouse. Data warehousing (materialized views) offers higheravailability and better query performance as all infor-mation can be retrieved from a single location, andthus is a suitable choice when high-performance queryprocessing and data analysis is critical. Similarly, thisapproach is advantageous when the informationsources are very expensive to access or even occasion-ally become unavailable, when network delays causehigh costs, or when the middle-layer tasks such astranslation or merging are too complex and ineffective,possibly requiring human input. Data warehousing has been found to be anextremely useful technology for a large number ofmodern applications. Such applications range over

Xin Zhang

Papers

System and method for automatic loading of an xml document defined by a document-type definition into a relational database including the generation of a relational schema therefor

System and method for synchronizing and/or updating an existing relational database with supplemental XML data

Algebraic XQuery Decorrelation with Order Sensitive Operations

Tomorrow's Web applications need a robust, efficient data warehouse system to succeed in dynamic Web-based environments.