A Systematic Performance Study of Object Database Management Systems

Many previous performance benchmarks for Object Database Management Systems (ODBMSs) have typically used arbitrary sets of tests based on what their designers felt were the characteristics of Engineering applications. Increasingly, however, ODBMSs are being used in non-engineering domains, such as Financial Trading, Clinical Healthcare, Telecommunications Network Management, etc. Part of the reason for this is that the technology has matured over the past few years and has become a less risky choice for organisations looking for better w'ays to manage complex data. However, the development of suitable application- or industry-specific benchmarks, based on actual performance studies, has not paralleled this growth. The research reported here approaches performance evaluation of ODBMSs pragmatically. It uses a combination of case studies and benchmark experiments to investigate the performance characteristics of ODBMSs for particular applications, following the successful use of this approach by Youssef [Youss93] for studying the performance of On- Line Transaction Processing (OLTP) applications for Relational Database Management Systems (RDBMSs). Six case studies at five organisations show’ that organisations consider a wide range of factors when undertaking their own performance studies or benchmarks. Furthermore, none of the studied organisations considered using any public benchmarks. Six current and derived benchmarks also highlight statistically significant performance differences between three major commercial products: Objectivity/DB, ObjectStore and UniSQL. These benchmarks indicate the suitability of the products tested for particular application domains. The research could not find any evidence at this time to support the concept of a generic or canonical performance workload for ODBMSs. This is demonstrated by the case studies and supported by the benchmark experiments. However, the research shows that performance benchmarks serve a very useful role in ODBMS evaluations and can help identify architectural and quality problems with products that would not otherwise be observed until significant application or system development was already in progress

Requirements for XML functionality in relational database management systems: an informix perspective

The eXtensible Markup Language (XML) is an evolving data format standard designed to simplify the exchange of data between disparate information systems. As Informix is in the business of information management, we need to provide mechanisms whereby our customers can take advantage of XML as it evolves. The authors present some of the XML specific features that are available in various Informix products

Querying tree-structured data using dimension graphs

Abstract. Tree structures provide a popular means to organize the in-formation on the Web. Taxonomies of thematic categories, concept hi-erarchies, e-commerce product catalogs are examples of such structures. Querying multiple data sources that use tree structures to organize their data is a challenging issue due to name mismatches, structural differ-ences and structural inconsistencies that occur in such structures, even for a single knowledge domain. In this paper, we present a method to query tree-structured data. We introduce dimensions which are sets of semantically related nodes in tree structures. Based on dimensions, we suggest dimension graphs. Dimension graphs can be automatically ex-tracted from trees and abstract their structural information. They are semantically rich constructs that provide query guidance to pose and evaluate queries on trees. We design a query language to query tree-structured data. A key feature of this language is that queries are not restricted by the structure of the trees. We present a technique for eval-uating queries and we provide necessary and sufficient conditions for checking query unsatisfiability. We also show how dimension graphs can be used to query multiple trees in the presence of structural differences and inconsistencies.