XQ2P: Efficient XQuery P2P Time Series Processing

In this demonstration, we propose a model for the management of XML time series (TS), using the new XQuery 1.1 window operator. We argue that centralized computation is slow, and demonstrate XQ2P, our prototype of efficient XQuery P2P TS computation in the context of financial analysis of large data sets (>1M values)

Seed Spillage from Grain Trailers on Road Verges during Oilseed Rape Harvest: An Experimental Survey

Context: Anthropogenic vectors enhance the natural dispersal capacity of plant seeds significantly in terms of quantity and distance. Human-mediated seed dispersal (i.e. anthropochory) greatly increases the dispersal of crop species across agroecosystems. In the case of oilseed rape (OSR), spillage of seeds from grain trailers during harvest has never been quantified. Methods: Our experimental approach involved establishing 85 seed trap-sites on the road verges of an agricultural area around the grain silo of Selommes (Loir-et-Cher, France). We recorded OSR spillage during harvest and applied a linear model to the data. Results: The amount of seed spilled was related positively to the area of the OSR fields served by the road, whereas the amount of seed spilled decreased with other variables, such as distance from the trap-site to the verge of the road and to the nearest field. The distance to the grain silo, through local and regional effects, affected seed loss. Local effects from fields adjacent to the road resulted in a cumulative spillage on one-lane roads. On two-lane roads, spillage was nearly constant whatever the distance to the silo due to a mixture of these local effects and of grain trailers that joined the road from more distant fields. From the data, we predicted the number of seeds lost from grain trailers on one road verge in the study area. We predicted a total spillage of 2.05610 6 seeds (64.76610 5) along the road length, which represented

Join and semijoin algorithms for a multiprocessor database machine

This paper presents and analyzes join and semijoin algorithms for a multiprocessor database machine

ESQL2 - extending SQL2 to support object-oriented ans deductive databases

Projet RODINESQL2 is an SQL2 upward-compatible database language that integrates in a uniform and clean way the essential concepts of relational, object-oriented and deductive databases. ESQL2 is intented for traditional data processing applications as well as more complex applications such as large expert systems. Therefore, ESQL's salient features are : a rich and extendible type system based on abstract data types (ADTs) which can be implemented in various programming languages ; complex object with object sharing by combining generic ADTs and object identity ; the capability of querying and updating relations of values or classes of objects using extended SQL syntax and semantics ; a Datalog-like deductive capability provided as an extension of the SQL view mechanism ; and control statements for programming stored procedures and multi-statement queries. As ESQL2 is a rich language, a graphical representation of ESQL2 database schemas and queries is proposed to simplify query formulation. A database is represented using extended entity-relationship diagrams. A query is pictured as a database view where only relevent parts of diagrams are used, in addition, types may be constrained by predicates. This representation yields an algorithm to translate ESQL2 queries in Datalog extended with object identifiers, functions and sets, thereby defining the semantics of ESQL2 queries. Thus, ESQL2 may be perceived as a SQL-compatible syntax for expressing extended Datalog queries

Concurrency control principles in distributed and centralized databases

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Bases de donnees: evaluation des programmes logiques recursifs par des fonctions recurrentes

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Leveraging Mediator Cost Models with Heterogeneous Data Sources

Projet RODINDistributed systems require declarative access to diverse data sources of information. One approach to solving this heterogeneous distributed database problem is based on mediator architectures. In these architectures, mediators accept queries from users, process them with respect to wrappers, and return answers. Wrapper provide access to underlying data sources. To efficiently process queries, the mediator must optimize the plan used for processing the query. In classical databases, cost-estimate based query optimization is an effective method for optimization. In a heterogeneous distributed databases, cost-estimate based query optimization is difficult to achieve because the underlying data sources do not export cost information. This paper describes a new method that permits the wrapper programmer to export cost estimates (cost estimate formulas and statistics). For the wrapper programmer to describe all cost estimates may be impossible due to lack of information or burdensome due to the amount of information. We ease this responsibility of the wrapper programmer by leveraging the generic cost model of the mediator with specific cost estimates from the wrappers. This paper describes the mediator architecture, the language for specifying cost estimates, the algorithm for the blending of cost estimates during query optimization, and experimental results based on a combination of analytical formulas and real measurements of an object database system

Les arbres de predicats

Nous proposons ici une nouvelle structure de données basées sur des arbres de prédicats utilisés pour regrouper les tuples d'une relation

ESQL : an extended SQL with object and deductive capabilities

Projet RODINESQL is an SQL upward-compatible database language that integrates in a uniform and clean way the essential concepts of relational, object-oriented and deductive databases. ESQL is intended for traditional data processing applications as well as more complex applications such as large expert systems. Therefore, ESQL's salient features are : a rich and extendible type system based on abstract data types (ADTs) implemented in various programming languages ; complex objects with object sharing by combining generic ADTs and object identity ; the capability of querying and updating relations containing simple or complex objects using SQL-compatible syntax and semantics ; and a Datalog-like deductive capability provided as an extension of the SQL view mechanism. ESQL's functional semantics enables uniform manipulation of ESQL data and should facilitate the implementation of the ESQL compiler