System R: Relational Approach to Database Management

Database Management Systems (DBMSs) are a ubiquitous and critical component of modern computing, and the result of decades of research and development in both academia and industry. Historically, DBMSs were among the earliest multi-user server systems to be developed, and thus pioneered many systems design techniques for scalability and reliability now in use in many other contexts. While many of the algorithms and abstractions used by a DBMS are textbook material, there has been relatively sparse coverage in the literature of the systems design issues that make a DBMS work. This paper presents an architectural discussion of DBMS design principles, including process models, parallel architecture, storage system design, transaction system implementation, query processor and optimizer architectures, and typical shared components and utilities. Successful commercial and open-source systems are used as points of reference, particularly when multiple alternative designs have been adopted by different groups.

Encyclopedia of Database Systems, 2009

Chapter 7 has presented models of databases; Chap. 8 discussed means to describe databases, and now we can finally look at actual database implementation problems. In this chapter we will proceed in a top-down fashion. We begin with methods derived from formal models and continue on to systems developed over time and regular use. The discussion in this chapter proceeds in the direction of increased binding, which causes loss of flexibility but increases the performance of systems. Such important implementation issues such as reliability, access protection, integrity, and data representation are not covered in this chapter; they are separately discussed in Chaps. 11, 12, 13, and 14. We concentrate on concepts, and do not present complete system descriptions, although many actual systems will be referenced to allow further study. Appendix B can be consulted for references about the systems named in this chapter. The exact syntax of examples based on these systems has been modified at times in order to provide continuity. The fact that a certain system is cited here as a commendable example does not imply an endorsement of this implementation for a given application but only reflects on the values of the concepts being discussed. 449 Objectives We have implied earlier a number of objectives for a database system design: 1 The ability to refer to data items without having knowledge of record or file structure and as a corollary: 2 The ability to change record or file content and structure without affecting existing database programs We also desire 3 The ability to handle related files within one general framework, so that the data in separate files can remain consistent and so that excessive redundancy in updating and storage can be avoided and 4 A description of the database integrating diverse points of view, so that this description can become a communication medium between data generators and information seekers In order to achieve these lofty goals, we will consider how to implement systems that use schemas to present high-level services while using file-based, record-oriented structures. Sec. 9-1 Issues in Database Implementation 451 9-1 ISSUES IN DATABASE IMPLEMENTATION In this introductory section we will introduce briefly some concepts that recur throughout this chapter. 9-1-1 Functionality and Generality Database-management systems can be built with a wide range of generality. A categorization of these approaches into three levels distinguishes systems which support a single application, several applications of the same type, or multiple types of applications. Some systems have developed through these three levels; others have been designed consciously to attack problems at one specific level. Single-Application Database Systems An organization establishes a database operation using available file system facilities, and designs application programs that interface to the database using a centrally maintained package which implements the required degree of data and structure description. The original airline reservation system at American Airlines, SABRE, many large information systems, such as MEDLARS (a system to query the medical literature), and military command and control systems are examples of this approach. Single-Application-Type Database Systems A group of users working in some type of application area recognizes the commonality of their needs. They or their vendor design a system to match their needs. User differences are incorporated into tables and schemas specific to the user. This step often follows success with a more single-minded system. Examples of this approach are the generalized airline reservation systems (PARS), clinical information systems (TOD, GEMISCH), and bills-of-materials systems (BOMP). Multiple-Application-Type Database Systems A vendor or academic group designs a system with the intent to serve the general database needs in a better fashion. An effort is made to provide a complete set of services. There will, of course, be a tendency to emphasize aspects relating to the experience of the designers, so that in practice a great deal of difference is found among the generalized systems. Another source for generalized systems is a continued evolution from single application or application-type services. An understanding of the history of generalized systems helps to explain features of their design. The development of the CODASYL specification and of the relational model for databases has provided a basis for generalized systems that are relatively independent of past history. Generalized systems developed independently encountered so far in the text are PRTV, RETRIEVE, SOCRATE, and SQL/DS. The IDS and IMS systems owe much to the BOMP applications.

Earlier DBMS software package was one integrated system where large centralized mainframe computers were used. The modern DBMS packages are modular in design, with a client/server architecture where hundreds of distributed workstations and personal computers are connected via communications network. There are various types of servers like Web servers, database servers, file servers, application servers and so on. A client module will run on a user workstation or personal computer. Typically, application programs and user interfaces that access the database run in the client module. The client module handles user interaction and provides the user-friendly interfaces such as forms or menu based GUIs. The server module handles data storage, access, search and other functions. The study of data models, schemas and instances is very important to understand database systems. 2.2. DATA MODELS, SCHEMAS, AND INSTANCES 2.2.1 Data Model A data model is a collection of concepts that can be used to describe the structure of the database. It is a type of data abstraction that is used to provide conceptual representation of data. It uses logical concepts that can be easily understood. A data model is a set of concepts that can be used to describe the structure of a database, which includes data types, relationships and data constraints etc. It also includes a set of basic operations for specifying retrievals and updates on the database. Also dynamic aspect or behavior of a database application is included in a data model. Categories of Data Models Data models are categorized based on the types of concepts that they provide to describe the database structure.

Database Management, 2024

This note provides a comprehensive examination of database management, covering fundamental concepts, principles, and contemporary practices in the field. The document begins by elucidating the foundational elements of databases, including data models, schemas, and normalization techniques. It delves into the role of database management systems (DBMS) as the central orchestrators of data organization, storage, retrieval, and manipulation. The note explores various types of databases, such as relational, NoSQL, and object-oriented databases, offering insights into their respective strengths, weaknesses, and use cases. Additionally, it discusses the significance of data integrity, security, and concurrency control within database systems, addressing the challenges and solutions associated with these critical aspects. A significant portion of the note is dedicated to query languages, with an emphasis on SQL (Structured Query Language) and its pivotal role in interacting with relational databases. The document also highlights emerging trends in database management, such as cloud-based databases, big data technologies, and the integration of artificial intelligence for enhanced data analytics. Furthermore, the note touches upon database administration, covering tasks such as backup and recovery, performance tuning, and user management. It concludes by examining the evolving landscape of database management, considering factors like the rise of distributed databases and the growing importance of scalability and flexibility in modern data ecosystems.

Debu, 1981

Database Engineering Bulletin is a quarterly publication of the IEEE Computer Society Technical Committee on Database Engineering. Its scope of interest includes: data structures and models, access strategies, access control techniques, database architecture, database machines, intelligent front ends, mass storage for very large data bases, distributed database systems and techniques, database software design and implementation, database utilities, database security and related areas. Contribution to the Bulletin is hereby solicited. News items, letters, technical papers, book reviews, meeting previews, summaries, case studies, etc., should be sent to the Editor. All letters tothe Editor will be considered for publication unless accompanied by a request to the con trary. Technical papers are unrefereed.

Deep Science Research, 2025

When implemented according to the model proposed by E. F. Codd in 1970, databases and their management systems are said to be relational, hence the term relational model. Codd showed that relational databases have significant advantages over previous hierarchical and network models. Relational modelling is the foundation of relational databases. It provides the basis for a high-level data language that can be used both by end users and by application developers and also supports the design of user views.

Databases based on relational, object-oriented, and object-relational models represent significant advances in database technologies. In the context of general-purpose database management systems, the fundamentals of database models are examined. A historical perspective on the evolution of major database models is provided. The principal concepts underlying relational, object-oriented, and object-relational database models are presented with examples. Finally, a brief view of database federation issues is introduced and served as the foundation for computerized databases are essential and inseparable components of most of today’s information systems and data base technology.

ACM Transactions on Database Systems, 1986

This paper deals with the transaction management aspects of the R* distributed database system. It concentrates primarily on the description of the R* commit protocols, Presumed Abort (PA) and Presumed Commit (PC). PA and PC are extensions of the well-known, two-phase (2P) commit protocol. PA is optimized for read-only transactions and a class of multisite update transactions, and PC is optimized for other classes of multisite update transactions. The optimizations result in reduced intersite message traffic and log writes, and, consequently, a better response time. The paper also discusses R*'s approach toward distributed deadlock detection and resolution.

Every technology has strengths and weaknesses, and relational database technology is no different. At this point in time, however, relational database management systems are the predominant storage technology; they are used to store information which is then available for easy retrieval based on various call procedures. While a database management system (DMS) controls storage, retrieval, security, and control of data within a database, a relational database management system (RDBMS) stores the data in a specific way. Other technologies are in the process of developing, but in their infancy not enough information is available for the average company to decide whether or not their use would be efficacious. RDBMS will be around for many years, but alternatives are gradually becoming available as technologies develop and improve. Companies need to remain on top of new developments, but remain very aware of limitations and how they can affect the company before jumping to new database systems. This paper critically evaluates the strengths and weaknesses of relational database technology.