摘要:
A method and apparatus for rewriting a database command containing an embedded XML expression such that the rewritten database command recites a text function, in lieu of the embedded XML expression, is provided. Advantageously, a DBMS may take advantage of the efficiencies in storing XML data within the database, while avoiding the generation of unnecessary XML elements in processing the query when the XML elements contribute nothing to the outcome of the query. Cost-base or rule-based analysis may be performed to determine how to rewrite a received database command. The database server may functionally evaluate the text function or may use an index defined on a column of the database. The text function may function as a primary filter or may reference a column upon which an index is defined, wherein the index operates at the same or higher level than a column being referenced in the embedded XML expression.
摘要:
A method and apparatus for rewriting a database command containing an embedded XML expression such that the rewritten database command recites a text function, in lieu of the embedded XML expression, is provided. Advantageously, a DBMS may take advantage of the efficiencies in storing XML data within the database, while avoiding the generation of unnecessary XML elements in processing the query when the XML elements contribute nothing to the outcome of the query. Cost-base or rule-based analysis may be performed to determine how to rewrite a received database command. The database server may functionally evaluate the text function or may use an index defined on a column of the database. The text function may function as a primary filter or may reference a column upon which an index is defined, wherein the index operates at the same or higher level than a column being referenced in the embedded XML expression.
摘要:
To associate XML data objects (“child objects”), stored in rows of relational or object-relational tables, with the appropriate XML data objects (“parent objects”) from which the child objects descend, tables that contain child objects (“out-of-line” tables) are constructed with an additional column. In one embodiment, this column stores values that identify the root objects, in the appropriate table, from which the respective child objects descend. Hence, the root object from which any given object descends is traceable by following the respective value back to the corresponding root object. In one embodiment, this column stores values that identify the complete XML hierarchical path, through multiple tables, back to the root object from which the respective child objects descend. Consequently, XML query language queries against XML documents stored in such tables can be rewritten as SQL queries against the data in the tables, even in the presence of cyclic constructs.
摘要:
To associate XML data objects (“child objects”), stored in rows of relational or object-relational tables, with the appropriate XML data objects (“parent objects”) from which the child objects descend, tables that contain child objects (“out-of-line” tables) are constructed with an additional column. In one embodiment, this column stores values that identify the root objects, in the appropriate table, from which the respective child objects descend. Hence, the root object from which any given object descends is traceable by following the respective value back to the corresponding root object. In one embodiment, this column stores values that identify the complete XML hierarchical path, through multiple tables, back to the root object from which the respective child objects descend. Consequently, XML query language queries against XML documents stored in such tables can be rewritten as SQL queries against the data in the tables, even in the presence of cyclic constructs.
摘要:
Techniques are described for executing queries that have XPath sections that specify unmappable paths. The techniques involve splitting the unmappable paths into (1) a mappable path fragment, and (2) an unmappable path fragment. After an unmappable path has been split into a mappable path fragment and an unmappable path fragment, the XPath section is replaced with a replacement XPath section. The replacement XPath section specifies two operations: a “mappable operation” that is based on the mappable path fragment, and an “unmappable operation” that is based on the unmappable path fragment. The portion of the replacement XPath section that specifies the mappable operation is rewritten to access underlying relational structures. Consequently, when the rewritten query is executed, a smaller amount of XML data needs to be materialized to evaluate the unmappable path fragment than would otherwise have been required to evaluate the original unmappable path.
摘要:
A database server that manages a database retrieves metadata that is stored, within the database, in association with a procedure that is stored in the database. Based on the metadata, a Web service definition is automatically constructed to describe the procedure as a Web service. The WSDL definition can be referenced to construct SOAP messages with the appropriate arguments and in the appropriate format which, when received, are converted to a suitable format for invoking execution of the procedure by the database server.
摘要:
Techniques for managing XML data associated with multiple execution units ensure that execution units are able to use XML data coming from other execution units. Such techniques are applicable when, but for the technique, an XML type value is produced in a particular form by one execution unit and is supposed to be consumed by another execution unit that is unable to process data in the particular form, and involves detecting that the foregoing situation exists and annotating information sent to an XML producer execution unit to cause the XML type value to be transformed into a canonical form that can be shared by all relevant execution units.
摘要:
Disclosed is a method and mechanism for processing expressions and operator trees. An approach is particularly useful to optimize processing of XML statements with respect to SQL operators. A top-down processing approach can be taken to directly output data from operators to a data stream. In addition, multiple processing approaches can be taken within a single expression tree, with some operators processed using the top-down approach and other operators processed with the bottom-up approach. Even data that can not be streamed is copied fewer times using this approach, intermediate values from bottom-up processing may still be streamed if it is used by an operator that is eligible for top-down processing.
摘要:
Techniques for managing XML data associated with multiple execution units ensure that execution units are able to use XML data coming from other execution units. Such techniques are applicable when, but for the technique, an XML type value is produced in a particular form by one execution unit and is supposed to be consumed by another execution unit that is unable to process data in the particular form, and involves detecting that the foregoing situation exists and annotating information sent to an XML producer execution unit to cause the XML type value to be transformed into a canonical form that can be shared by all relevant execution units.
摘要:
An XQuery access API is described, for providing access to XML data from a data source, using the XQuery language. A requestor can request, from a server, performance of an operation on XML data, wherein request messages and response messages conform to the Simple Object Access Protocol (SOAP). Request and response messages can be transmitted using Hypertext Transfer Protocol (HTTP) or Hypertext Transfer Protocol over Secure Socket Layer (HTTPS). The format of the request and response messages is specified in a definition of a Web service, where the definition conforms to the Web Service Description Language (WSDL).