A Framework for the Study of Query Decomposition for Heterogeneous Distributed Database Management Systems

This paper presents a framework for the study of the query decomposition translation for heterogeneous record -oriented database management systems. This framework is based on the applied database logic representation of relational, hierarchical and network databases. The input to the query decomposition translation is the query graph which is derived from the complex to basic, external to conceptual and logical optimization translations. Once the query graph is obtained the objective of the query decomposition translation is to break up a query expressed in terms of the actual or conceptual databases into its component parts or subqueries and find a strategy indicating the sequence of primitive or fundamental operations and their corresponding processing sites in the network necessary to answer the query. The query processing strategy is usually chosen so as to satisfy some performance criterion such as response time reduction. Contingent on after each primitive operation. The prequery decomposition translation, the query decomposition translation and the size estimation issues are presented through an example based on the current implementation of the Distributed Access View Integration Database (DAVID) currently being built at NASA's Goddard Space Flight Center (GSFC). The choice of a query processing strategy is the successful estimation of intermediate result

Heterogeneous Distributed Data Base Management Systems

This work analyzes the design and implementation issues of Heterogeneous Distributed Data Base Management Systems (HDDBMS). To date, HD-DBMS research projects and implementa tions have been limited. The few such systems which have been constructed provide valuable insight into the nature of problems faced due to heterogeneity. Some of these systems (SIRIUS-DELTA, MULTIBASE, AIDA) , are presented in order to examine their solutions to the problems. The major issues described in the thesis are: the architec ture of the distributed system; query translation; schema mapping; and integration of the schemata within the hetero geneous distributed database, in seeking solutions to these issues, an architecture for a HD-DBMS is proposed

Initial Observations on Query Based Sampling in Distributed CLIR

Cross Language Information Retrieval (CLIR) enables people to search information written in different languages from their query languages. Information can be retrieved either from a single cross lingual collection or from a variety of dis-tributed cross lingual sources. This paper pre-sents initial results exploring the effectiveness of distributed CLIR using query-based sampling techniques, which to the best of our knowledge has not been investigated before. In distributed retrieval with multiple databases, query-based sampling provides a simple and effective way for acquiring accurate resource descriptions which helps to select which databases to search. Obser-vations from our initial experiments show that the negative impact of query-based sampling on cross language search may not be as great as it is on monolingual retrieval

Object-oriented querying of existing relational databases

In this paper, we present algorithms which allow an object-oriented querying of existing relational databases. Our goal is to provide an improved query interface for relational systems with better query facilities than SQL. This seems to be very important since, in real world applications, relational systems are most commonly used and their dominance will remain in the near future. To overcome the drawbacks of relational systems, especially the poor query facilities of SQL, we propose a schema transformation and a query translation algorithm. The schema transformation algorithm uses additional semantic information to enhance the relational schema and transform it into a corresponding object-oriented schema. If the additional semantic information can be deducted from an underlying entity-relationship design schema, the schema transformation may be done fully automatically. To query the created object-oriented schema, we use the Structured Object Query Language (SOQL) which provides declarative query facilities on objects. SOQL queries using the created object-oriented schema are much shorter, easier to write and understand and more intuitive than corresponding S Q L queries leading to an enhanced usability and an improved querying of the database. The query translation algorithm automatically translates SOQL queries into equivalent SQL queries for the original relational schema

Implementing Database Coordination in P2P Networks

We are interested in the interaction of databases in Peer-to-Peer (P2P) networks. In this paper we propose a new solution for P2P databases, that we call database coordination. We see coordination as managing semantic interdependencies among databases at runtime. We propose a data coordination model where the notions of Interest Groups and Acquaintances play the most crucial role. Interest groups support the formation of peers according to data models they have in common; and acquaintances allow for peers inter-operation. Finally, we present an architecture supporting database coordination and show how it is implemented on top of JXTA

A Framework for XML-based Integration of Data, Visualization and Analysis in a Biomedical Domain

Biomedical data are becoming increasingly complex and heterogeneous in nature. The data are stored in distributed information systems, using a variety of data models, and are processed by increasingly more complex tools that analyze and visualize them. We present in this paper our framework for integrating biomedical research data and tools into a unique Web front end. Our framework is applied to the University of Washington’s Human Brain Project. Specifically, we present solutions to four integration tasks: definition of complex mappings from relational sources to XML, distributed XQuery processing, generation of heterogeneous output formats, and the integration of heterogeneous data visualization and analysis tools

An Ontology Based Method to Solve Query Identifier Heterogeneity in Post-Genomic Clinical Trials

The increasing amount of information available for biomedical research has led to issues related to knowledge discovery in large collections of data. Moreover, Information Retrieval techniques must consider heterogeneities present in databases, initially belonging to different domains—e.g. clinical and genetic data. One of the goals, among others, of the ACGT European is to provide seamless and homogeneous access to integrated databases. In this work, we describe an approach to overcome heterogeneities in identifiers inside queries. We present an ontology classifying the most common identifier semantic heterogeneities, and a service that makes use of it to cope with the problem using the described approach. Finally, we illustrate the solution by analysing a set of real queries