Xcerpt is a declarative pattern based query and transformation language for semistructured data that like xml that bases on concepts and techniques of logic programming. Xcerpt uses both forward and backward chaining for program evaluation. While forward chaining is used for operations like view materialization, backward chaining is used in querying databases such as the web. This thesis presen...

In large databases particularly in distributed database, query response time plays an important role as timely access to information and it is the basic requirement of successful business application. A data warehouse uses multiple materialized views to efficiently process a given set of queries. Quick response time and accuracy are important factors in the success of any database. The material...

Numerous data intensive applications demand the efficient processing of a new type of query, which is called a progressive query (PQ). A PQ consists of a set of unpredictable but inter-related step-queries (SQ) that are specified by its user in a sequence of steps. A conventional DBMS was not designed to efficiently process such PQs. In our earlier work, we introduced a materialized view based ...

The join operator is fundamental in relational database systems. Evaluating join queries on large tables is challenging because records need to be efficiently matched based on a given key. In this work, we analyze join queries in SQL with large tables in which a foreign key may be null, invalid or valid, given a referential integrity constraint. We conduct an extensive join performance evaluati...

The ErbB receptor tyrosine kinases evolved as key regulatory entities enabling the extracellular milieu to communicate with the intracellular machinery to bring forth the appropriate biological response in an ever-changing environment. Since its discovery, many aspects of the ErbB family have been deciphered, with emphasis on aberration of signaling in human diseases. However, only now, with th...

A powerful, easy-to-use querying environment is without doubt one of the most important components in a multidimensional database. Its effectiveness is influenced by many aspects, both logical (data model, integration, policy of view materialization, etc.) and physical (multidimensional or relational storage, indexes, etc.). Multidimensional querying is often based on the core concepts of multi...

This paper describes the direct relationship between the perception of citizenship and its material expression, with emphasis on how changing expression obliges a rethink of the channels of mediation between citizens and their elected leaders. An analysis of the French voting ritual will show how our voting system is embedded in a specific cultural conception of citizenship . The emergence of n...

A data warehouse is a data repository which collects and maintains a large amount of data from multiple distributed, autonomous and possibly heterogeneous data sources. Often the data is stored in the form of materialized views in order to provide fast access to the integrated data. One of the most important decisions in designing a data warehouse is the selection of views for materialization. ...

The DL-Lite family are description logics specifically designed for ontology-based data access (OBDA). In this setting, an ontology with background knowlege (a TBox) can be seen as a conceptual view over data repositories (ABoxes), and data can be accessed via query answering services. Common techniques for query answering in DL-Lite are (pure) rewriting and combined approaches. In the rewritin...

Database federation is becoming an increased reality for business and clinical organizations due to rapid data accumulation, making a single, monolithic data warehouse difficult to achieve. A commonly used technique to decrease query execution time in data warehousing environments is to precompute and store beneficial views. Known as the view selection problem, this process seeks to identify th...