The invention relates to a method of managing a database. The database includes a central database ( 3 ) and separate partially replicated databases ( 23 - a , 23 - b , 23 - c ). Each partially replicated database resides on a separate node ( 21 - a , 21 - b , 21 - c ). Each replicated database has an associated visibility strength. The method of managing a database determines the visibility strength of a partially replicated database to data being propagated, determines therefrom the visibility of the partially replicated database to the data being propagated, and propagates the data to a partially replicated database only if the node of the partially replicated database has visibility to the data.

Method of determining visibility to a remote database client of a plurality of database transactions having variable visibility strengths

Disclosed herein are various exemplary systems and methods for linking entity references to entities and identifying associations between entities. In particular, a method for identifying an entity from a plurality of entity references, each entity reference being linked with a separate ghost entity, is provided. The method comprises the steps of comparing an entity reference of a first ghost entity with an entity reference of a second ghost entity to determine a match probability between the entity reference of the first ghost entity and the entity reference of the second ghost entity, linking the entity reference of the first ghost entity additionally with the second ghost entity and the entity reference of the second ghost entity additionally with the first ghost entity when the match probability is greater than or equal to a match threshold and repeating the steps of comparing and linking for one or more ghost entity pairings possible from the ghost entities. The method further comprises determining, for one or more entity references linked to a ghost entity, a score for the entity reference based at least in part on a match probability between the entity reference and a value representing the one or more entity references linked to the ghost entity and identifying the ghost entity as an actual entity based at least in part on one or more scores for the one or more entity references linked to the ghost entity.

Method and system for processing data records

Network operating system

Relational XQuery systems try to re-use mature relational data management infrastructures to create fast and scalable XML database technology. This paper describes the main features, key contributions, and lessons learned while implementing such a system. Its architecture consists of (i) a range-based encoding of XML documents into relational tables, (ii) a compilation technique that translates XQuery into a basic relational algebra, (iii) a restricted (order) property-aware peephole relational query optimization strategy, and (iv) a mapping from XML update statements into relational updates. Thus, this system implements all essential XML database functionalities (rather than a single feature) such that we can learn from the full consequences of our architectural decisions. While implementing this system, we had to extend the state-of-the-art with a number of new technical contributions, such as loop-lifted staircase join and efficient relational query evaluation strategies for XQuery theta-joins with existential semantics. These contributions as well as the architectural lessons learned are also deemed valuable for other relational back-end engines. The performance and scalability of the resulting system is evaluated on the XMark benchmark up to data sizes of 11GB. The performance section also provides an extensive benchmark comparison of all major XMark results published previously, which confirm that the goal of purely relational XQuery processing, namely speed and scalability, was met.

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MonetDB/XQuery: a fast XQuery processor powered by a relational engine

Methods, systems and computer program products for delivering information to a user in one or more preferred delivery media are provided. Preferred delivery media includes, but is not limited to, e-mail, HTML, fax, printed copy, and mail. A user profile, indicating a user's preferred delivery medium (or media), is retrievably stored. When a user requests information, the user's profile is searched to determine the preferred delivery medium (or media) within which to deliver the requested information to the user. The requested information is retrieved, formatted for the preferred delivery medium, and then delivered to the user in the preferred medium. If the information is delivered to a user in multiple media, a consistent format among the various delivery media is maintained. The integrity of information delivered to a user is also verifiable, regardless of the delivery medium.

Systems, methods, and computer program products for delivering information in a preferred medium

XML languages, such as XQuery, XSLT and SQL/XML, employ XPath as the search and extraction language. XPath expressions often define complicated navigation, resulting in expensive query processing, especially when executed over large collections of documents. In this paper, we propose a framework for exploiting materialized XPath views to expedite processing of XML queries. We explore a class of materialized XPath views, which may contain XML fragments, typed data values, full paths, node references or any combination thereof. We develop an XPath matching algorithm to determine when such views can be used to answer a user query containing XPath expressions. We use the match information to identify the portion of an XPath expression in the user query which is not covered by the XPath view. Finally, we construct, possibly multiple, compensation expressions which need to be applied to the view to produce the query result. Experimental evaluation, using our prototype implementation, shows that the matching algorithm is very efficient and usually accounts for a small fraction of the total query compilation time.

/pdf/a-framework-for-using-materialized-xpath-views-in-xml-query-3d3k35j13f.pdf

A framework for using materialized XPath views in XML query processing

An automated methodology, and an apparatus for practicing the methodology, which enables the power and flexibility inherent in shared nothing parallel database systems (MPP) to be utilized on complex queries which have, heretofore, contained query elements requiring local computation or local coordination of data computation performed across the nodes of the distributed system. The present invention provides these features and advantages by identifying and marking the subgraphs containing these types of query elements as "no TQ zones" in the preparation phase prior to optimization. When the optimizer sees the markings, it builds a plan that will force the computation of the marked subgraphs to be in the same section. This preparation phase also provides the partitioning information for all inputs to the "no TQ zones". This allows the bottom-up optimizer to correctly plan the partitioning for the "no TQ zones". These partitionings can force the operation to a single-node, the coordinator node, the catalog node, or to a particular partition class on multiple nodes, or nodegroups.

Shared nothing parallel execution of procedural constructs in SQL

This paper describes the overall architecture and design aspects of a hybrid relational and XML database system called System RX. We believe that such a system is fundamental in the evolution of enterprise data management solutions: XML and relational data will co-exist and complement each other in enterprise solutions. Furthermore, a successful XML repository requires much of the same infrastructure that already exists in a relational database management system. Finally, XML query languages have considerable conceptual and functional overlap with relational dataflow engines. System RX is the first truly hybrid system that comingles XML and relational data, giving them equal footing. The new support for XML includes native support for storage and indexing as well as query compilation and evaluation support for the latest industry-standard query languages, SQL/XML and XQuery. By building a hybrid system, we leverage more than 20 years of data management research to advance XML technology to the same standards expected from mature relational systems.

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System RX: one part relational, one part XML

A method for using pre-computed information stored in auxiliary structures to speed up processing of expensive queries on hierarchical documents such as XML documents being queried using XPath. The invention defines a taxonomy of such structures such as indexes and materialized views for storing pre-computed XPath results (PXRs), determines what portion of the query can be evaluated by the structures, and computes the compensation for the results generated by the structures. The invention detects all structures applicable to the query and rewrites the query to use such structures, speeding up the performance of the queries. The invention identifies the matching structures by detecting containment mappings between XPath expressions in the query and the structure. The invention also includes a new representation for XPath expressions that is rich enough to express all features of XPath.

XPath containment for index and materialized view matching

An automated system for detecting and preventing mutating table violations of database integrity in a SQL query before generation and selection of an optimal query execution plan (QEP). This system modifies the query graph model (QGM) to restrict the choice of execution plans to those that avoid mutating table integrity (MTI) violations, thereby forcing database integrity during table mutation when executing the optimal QEP. Mutating table integrity violations are detected by evaluating the position in the QGM of each write-node referencing a particular base table with respect to each of the positions of all other read- and write-nodes referencing of the same base table. Every common-referencing node pair is tested for sequencing conflicts and a data-flow dam is inserted in the QGM where necessary or a poke query is inserted between the nodes to force the completion of the execution of one node before initiating execution of the other common-referencing node. The system of this invention allows processing of all non-cyclic and most cyclic SQL queries known to cause mutating table integrity violations, such as queries having searched and positioned inserts, deletes and updates, and row-level triggers.

Roberta Jo Cochrane

Papers

A framework for using materialized XPath views in XML query processing

Shared nothing parallel execution of procedural constructs in SQL

System RX: one part relational, one part XML

XPath containment for index and materialized view matching

Synchronization of SQL actions in a relational database system