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:
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 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:
A method and system are provided for determining whether a given path is an indexed path of XML documents stored in a database management system. A finite state machine is built using the path subsetting rules specified by a user. The finite state machine is traversed using the given path. If any accepting states are reached during the traversal of the finite state machine, the given path is determined to matching the path subsetting rules.
摘要:
A method and system for evolving XML-schema-based data to conform to an evolved XML schema is disclosed. Based on an existing XML schema and an instance document that is based on the existing XML schema, an XML-schema-independent form of the instance document is generated. Based on a set of specified transformations and the XML-schema-independent form of the instance document, an evolved instance document is generated. The evolved instance document conforms to an evolved XML schema that incorporates changes to the existing XML schema. Techniques described herein are flexible enough to accommodate a wide variety of evolutions to XML schemas.
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:
Techniques are provided for indexing XML documents using path subsetting. According to one embodiment, a PATH table created for storing one row for each indexed node of the XML documents using user-defined criteria. The user-defined criteria are used to determine which nodes of XML documents to included in The PATH TABLE. The PATH table row for a node includes (1) information for locating the XML document that contains the node, (2) information that identifies the path of the node, and (3) information that identifies the position of the node within the hierarchical structure of the XML document that contains the node. Use of the user defined criteria is transparent to any query improves DML indexes overhead costs.
摘要:
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.
摘要:
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.