摘要:
A method and system are provided for extracting a valid, self-contained fragment for a node in a XML document stored in a database management system. An XML index is used to identify a location in which XML fragment data corresponding to the node is located. Ancestors of the node are identified and examined for any information needed for the proper interpretation of the fragment. If an ancestor node contains such needed information, this information is patched into the XML fragment to ensure that the fragment is a valid, self-contained XML fragment.
摘要:
An XML document can be represented in a compact binary form that maintains all of the features of XML data in a useable form. In response to a request for a modification (e.g., insert, delete or update a node) to an XML document that is stored in the compact binary form, a certain representation of the requested modification is computed for application directly to the binary form of the document. Thus, the requested modification is applied directly to the persistently stored binary form without constructing an object tree or materializing the XML document into a corresponding textual form. Taking into account the nature of the binary form in which the document is encoded, the bytes that actually require change are identified, including identifying where in the binary representation the corresponding actual changes need to be made.
摘要:
In a multi-tier data server system, data from the first tier is cached in a mid-tier cache of the middle tier. Access control information from the first tier for the data is also cached within the mid-tier cache. Caching the security information in the middle tier allows the middle tier to make access control decisions regarding requests for data made by clients in the outer tier.
摘要:
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.
摘要:
A database server registers an XML schema and determines a database representation for the XML schema and mapping information, determining what database types should be used to represent an XML schema and/or how instances of the XML schema are stored by a database system. The mapping information indicates the mapping between the constructs declared in the XML schema and the constructs included in the appropriate database representation. The XML schema may contain annotations that describe one or more properties of a database representation of an XML date-time type. Based on the annotations, the database determines an appropriate database representation and generates mapping information mapping the declaration of the XML date-time type of the XML schema to the constructs of the database representation.
摘要:
Described herein is a system for “lazy” manifestation of XML documents. In lazy manifestation, only portions of an XML document that contain data of interest (e.g., a particular element or attribute requested by an application) are manifested. The term “manifesting a portion of an XML document” refers to creating an in-memory representation of the portion and incorporating it into existing in-memory representation of an XML document, if any. These portions are referred to herein as a loadable unit. A loadable unit is a set of one or more nodes in an XML document, where when there is need to manifest a node in the set, other nodes in the loadable unit are manifested too. Loadable units may, but not necessarily, correlate to content structures that store the nodes. A loadable unit may be the nodes whose content is contained in a row.
摘要:
Techniques are provided for facilitating uniform access control to data managed by a database server that can emulate hierarchically organized systems, whether the data is accessed through hierarchical or relational access mechanisms. A database server that can emulate hierarchically organized systems uses separate relational or object-relational database tables to store the content of the resources that belong to a hierarchy (the “content structures”) and information that captures the hierarchy (the “hierarchy structures”). Both types of structures contain access control data that define consistent user access privileges. To determine access privileges for a user requesting access to data in the database, access control information is accessed in the hierarchy structures when the request is made through the hierarchical access mechanism, or accessed in the content structures when the request is made through a relational access mechanism. Access control is consistent between the hierarchical or relational access mechanisms because access through either is governed by user access data that reflects the same privileges.
摘要:
A method and system are provided for maintaining an XML index in response to piece-wise modifications on indexed XML documents. The database server that manages the XML index determines which nodes are involved in the piece-wise modifications, and updates the XML index based on only those nodes. Index entries for nodes not involved in the piece-wise modifications remain unchanged.
摘要:
A method, mechanism, and computer program product for storing, accessing, and managing XML data is disclosed. The approach supports efficient evaluation of XPath queries and also improves the performance of data/fragment extraction. The approach can be applied to schema-less documents. The approach is applicable to all database systems and other servers which support storing and managing XML content. In addition, the approach can be applied to store, manage, and retrieve other types of unstructured or semi-structured data in a database system.