Patent application number | Description | Published |
20080249990 | Accessing data from asynchronously maintained index - A method and apparatus for computing queries in a way that is consistent with an index and the underlying base table is provided. A query is computed such that it is consistent with the state of an index and base table as of the last point at which the index and table were synchronized. For example, if an index is maintained asynchronously then it is not necessarily consistent with its base table when a query is to be run against the table and the index. Therefore, the query is computed such that it will be consistent with the last point at which the index and the table were synchronized. In one embodiment, a System Change Number (SCN) of the last successful synchronization operation is used to perform a flashback query on the table. | 10-09-2008 |
20090019077 | Accelerating value-based lookup of XML document in XQuery - A method and apparatus for accelerating value-based lookups of XML documents in XQuery is provided. XML indices can help to optimize SQL queries of XML documents stored in object-relational databases. Certain SQL/XML functions such as XMLTABLE( ) use XQuery expressions to query XML documents. Previously, such queries could not use the XML index because the PATH table of the XML index was not defined for XQuery semantics. Techniques described herein extend the XML index for use with queries that require evaluation of XQuery expressions. Consequently, techniques described herein accelerate value-based lookups of XML documents in XQuery by introducing the possibility of an index-assisted evaluation of XQuery expressions. | 01-15-2009 |
20090037368 | FAST PATH LOADING OF XML DATA - Techniques for implementing fast loading of binary XML into a binary XML database repository are provided. A client application reduces the processing burden on the repository by doing pre-processing of the binary XML data prior to loading. | 02-05-2009 |
20090037369 | Using sibling-count in XML indexes to optimize single-path queries - A method and apparatus are provided for using sibling-counts in XML indices to optimize single-path queries. Using a b-tree XML index with a SQL query logarithmically reduces the number of disk accesses by passing over index entries where it is determined that a match will not be found. However, because certain index entries are passed over, it is impossible to ascertain if a path expression occurs more than once in the XML index, as certain queries sometimes require. This hurdle can be overcome by maintaining a sibling count with each node entry in the XML index. Because the sibling count is stored with the index entry, the index will reveal whether the matching node is single or has other siblings. In additional to re-writing the original query for optimization by use of an XML index, it will be re-written to check for a single-path condition in the index. | 02-05-2009 |
20090112890 | EFFICIENT UPDATE OF BINARY XML CONTENT IN A DATABASE SYSTEM - Various techniques are described hereafter for improving the efficiency of updating XML documents in a content repository, such as a database system. Specifically, techniques are described for updating an XML document by dynamically merging a stream of XML data from the document with update information. Techniques are also described for efficient validation of XML documents. Because of the manner of the updates, specifically because the XML data being updated is in the form of a stream, the database system validates only those portions of the stream of XML data that have been updated. In the alternative, the database system validates that portion of the XML data that is associated with the parent node of the portion of XML data that has been updated. | 04-30-2009 |
20090125480 | Combining Streaming And Navigation For Evaluating XML Queries - A query is rewritten to combine streaming evaluation and XML index evaluation. The query is rewritten to include a streaming operator (e.g. function) that, when executed, uses streaming evaluation. Further, the query is rewritten so that XML index evaluation of a path expression also produces location information that identifies the location of a node within an XML document. The streaming operator is able to exploit the location information to begin and end scanning rather than scanning the entire XML document. | 05-14-2009 |
20090125494 | GLOBAL QUERY NORMALIZATION TO IMPROVE XML INDEX BASED REWRITES FOR PATH SUBSETTED INDEX - Techniques for processing a query that includes a path expression are provided. A query processor determines whether an XML index may be used to execute the query instead of having to scan multiple XML documents. The query is parsed and normalized, which results in multiple normalized path expressions that are based on the original path expression. If the XML index is a path-subsetted index, then the query processor generates annotated path expressions based on the normalized path expressions. The query processor determines whether each of the annotated path expressions is satisfiable by the path-subsetted XML index. If so, then the XML index is used to process the query. | 05-14-2009 |
20090125495 | OPTIMIZED STREAMING EVALUATION OF XML QUERIES - A database system may perform a streaming evaluation of an XPath expression by utilizing an XPath evaluation component in tandem with an XML event-streaming component. For a more optimal filtered streaming evaluation, the XML event-streaming component may provide an interface whereby the evaluation component sends certain criteria to the event-streaming component when requesting an XML event. The criteria may be based on a next unmatched step in the XPath expression. In response to the request for an XML event, the event-streaming component may only return events that match the criteria. The evaluation component may be, for example, a compiled state machine for the XPath expression. The criteria may be pre-compiled for each possible state in the state machine. The event-streaming component may also utilize the criteria along with schema information to skip parsing of certain segments of XML data. | 05-14-2009 |
20090125693 | TECHNIQUES FOR MORE EFFICIENT GENERATION OF XML EVENTS FROM XML DATA SOURCES - One may increase the efficiency of an XML event-generating process by reducing the number of requests to allocate or deallocate system memory. Such reduction may occur as the result of pre-allocating a memory chunk of sufficient size to contain all of the memory buffers required by a particular event-generating process. Instead of allocating new memory chunks for new memory buffers, an application may store any required buffers within the pre-allocated memory chunk. A sufficient memory size may be estimated by performing the event-generating process on a training set of XML documents. Also, an application may re-use buffers during the process or between different iterations of the process, thus avoiding the need to deallocate and reallocate memory that is essentially being used for the same purpose. | 05-14-2009 |
20130318109 | ISOLATION FOR APPLICATIONS WORKING ON SHARED XML DATA - A mechanism is provided for detecting and disregarding application specific nodes contained in shared XML documents. The techniques described involve determining one or more application specific nodes within XML documents and performing path expression evaluations of the XML documents as if the nodes are not present. In one embodiment, a mechanism is provided by which a user may specify the criterion that determine which subset of node in XML documents are to be ignored from path expression evaluations and evaluating a query that specifies a path operation based on a path and ignoring said identified nodes when evaluating said path operation. | 11-28-2013 |