ON IMPLEMENTING GRAPH REPRESENTATIONS

The three most common graph representations, namely the adjacency matrix, one way adjacency lists and adjacency multilist, are implemented in PASCAL and their performance evaluated for twelve graphs typical to computer network configurations. We show that both adjacency multilist and one way adjacency lists are preferred over the adjacency matrix representation. Although their implementation is Slightly more complicated it out performs the latter by a factor of at least 5

MANAGEMENT TOOLS ASSOCIATED WITH THE DEVELOPMENT OF COMPUTER SOFTWARE PRODUCTS

No abstract available

MICROCOMPUTER BASED DATABASE MANAGEMENT SYSTEMS IN SUPPORT OF OFFICE AUTOMATION

The evolutionary advancements in microprocessor technology as it relates to database management systems (DBMSs) are dis¬cussed. Practice and experience with five commercially available database management systems are reported, based mostly on data gathered from a series of interviews focusing on comparison among systems. Several prototype systems specifically designed to meet the needs of office information systems are identified, their conceptual framework ascertained and capabilities described. Finally, remarks on the limitations and future of microcomputer based DBMSs are made

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

Cluster Algebra: A Query Language for Heterogeneous Databases

This report describes a query language based on algebra for heterogeneous databases. The database logic is used as a uniform framework for studying the heterogeneous databases. The data model based on the database logic is referred to as cluster data model in this report. Generalized Structured Query Language (GSQL) is used for expressing ad-hoc queries over the relational, hierarchical and network database uniformly. For the purpose of query optimization, a query language that can express the primitive heterogeneous database operations is required. This report describes such a query language for the clusters (i.e., heterogeneous databases). The cluster algebra consists of (a) generalized relational operations such as selection, union, intersection, difference, semi-join, rename and cross-product; (b) modified relational operations such as normal projection and normal join; and (c) new operations such as normalize, embed, and unembed