Mermaid—A front-end to distributed heterogeneous databases

Middleware has become an essential component for almost every distributed database system. It uses wrappers when integration is achieved for heterogeneity. Different middleware systems have been produced aiming for a better performance. In this paper a new middleware system for heterogeneous distributed databases (HDDBs) called Open-Gate is proposed. Its main objective is to provide an efficient system with the characteristics of autonomy, scalability, reliability, and high performance. In addition, it can handle a huge number of users overcoming the bottleneck problem or loss of user's queries. Experimental results show that, the proposed system achieved high performance compared to other systems.

Information Sciences, 1989

Many databases are now accessible through computer networks, and users frequently have data of interest in different databases. Manipulations of such data call for functions that do not exist in classical manipulation languages and database systems. A new type of data manipulation languages is needed, called multidatabase manipulation languages. We describe the multidatabase language MSQL, designed for the manipulation of data from different relational databases. MSQL is an extension of SQL, which has become the standard for relational database systems.

1997

The Carnot project was an ambitious research project in heterogeneous databases. It integrated a variety oftechniques to address a wide range of problems in achieving interoperation in heterogeneous environments. Here we describe some of the major implemented applications of this project. These applications concern (a) accessing a legacy scienti c database, (b) automating a work ow involving legacy systems, (c) cleaning data, and (d) retrieving semantically appropriate information from structured databases in response to text queries. These applications support scienti c decision support, business process management, data integrity enhancement, and analytical decision support, respectively. They demonstrate Carnot's capabilities for (a) heterogeneous query processing, (b) relaxed transaction and work ow management, (c) knowledge discovery, and (d) heterogeneous resource model integration.

IEEE Journal on Selected Areas in Communications, 2000

Mermaid is a testbed system which provides integrated access to multiple databases. We have developed two query optimization algorithms for Mermaid. The semijoin algorithm tends to reduce the data transmission cost while the replicate algorithm reduces the processing cost. In this paper, we present an algorithm which inkgrates the features of these two algorithms to optimize the processing cost as well as the transmission cost. Particularly, we consider a dynamic network environment where processing speeds at each site and transmission speeds at each link can be variable. Moreover, distributed processing of aggregates is considered based on the functional dependency among the fragment attribute, the aggregate attribute, and the group-by attribute. We also apply semantic information for efficient query processing.

IEEE Transactions on knowledge and Data …, 1998

Accessing many data sources aggravates problems for users of heterogeneous distributed databases. Database administrators must deal with fragile mediators, that is, mediators with schemas and views that must be significantly changed to incorporate a new data source. When implementing translators of queries from mediators to data sources, database implementors must deal with data sources that do not support all the functionality required by mediators. Application programmers must deal with graceless failures for unavailable data sources. Queries simply return failure and no further information when data sources are unavailable for query processing. The Distributed Information Search COmponent (DISCO) addresses these problems. Data modeling techniques manage the connections to data sources, and sources can be added transparently to the users and applications. The interface between mediators and data sources flexibly handles different query languages and different data source functionality. Query rewriting and optimization techniques rewrite queries so they are efficiently evaluated by sources. Query processing and evaluation semantics are developed to process queries over unavailable data sources. In this article, we describe 1) the distributed mediator architecture of DISCO; 2) the data model and its modeling of data source connections; 3) the interface to underlying data sources and the query rewriting process; and 4) query processing semantics. We describe several advantages of our system.

International Journal of Information Technology and Computer Science, 2012

This paper presents the architecture for accessing heterogeneous databases. Two major processes in this architecture which are extracting SQL statement and ontology. The algorithms for extracting SQL statement was created and tested in order to improve time performance during searching and retrieving process. Ontology approach was implemented and combined with these algorithms. In ontology approach, web semantic was implemented in order to retrieve only relevant data from database. A prototype based on this architecture was developed using JAVA technology. JAVA technology was chosen because this technology have Jena library. This library is provide API and support SPARQL. Several experiments have been executed and tested. The result indicates this architecture able to improve web query processing in term of time. The result also indicates this architecture able to retrieve and displayed more relevant data to web users.

Users extract knowledge from the database by posing Quires. Most of the users submit SQL Query to extract information from the database. This makes a restriction on users to be familiar with SQL tool. Our proposal is to integrate the existing different database schemas into a single common format. It is widely recognized that integration of database and information retrieval is gaining more importance recently. To enable convenient access to the data organized in different database schemas, we have proposed a new Heterogeneous Data Base Connectivity (HDBC) architecture with graphical user interaction that can be used even by a novice person to create, manipulate and extract information in any database schema. The proposed algorithm also gives provision to export table from one database to another and supports excellent searching capabilities. User friendly interaction is ensured and hence this work enables the end user to retrieve information in an efficient manner from the database organized in different schema and can easily integrate and share the processed information across different applications.

1993

At North Dakota State University and IBM Rochester, MN, a development project is underway for a Heterogeneous Distributed Database System which includes object oriented data stores. The system is called the Heterogeneously Distributed Request Orderer (HYDRO). We view the object model as an extension of the relational model. When HYDRO connects autonomous local database systems as well as object oriented data stores into one unified system, we refer to it as OOHYDRO. In this paper we show how global serializability and atomic commitment can be attained in this setting.