Journal ArticleDOI
The theory of joins in relational databases
TLDR
An efficient algorithm to determine whether the join of several relations is semantically meaningful (lossless) and an efficient algorithmto determine whether a set of relations has a subset with a lossy join are given.Abstract:
Answering queries in a relational database often requires that the natural join of two or more relations be computed. However, the result of a join may not be what one expects. In this paper we give efficient algorithms to determine whether the join of several relations has the intuitively expected value (is lossless) and to determine whether a set of relations has a subset with a lossy join. These algorithms assume that all data dependencies are functional. We then discuss the extension of our techniques to the case where data dependencies are multivalued.read more
Citations
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Journal ArticleDOI
Extending the database relational model to capture more meaning
TL;DR: In this paper, the relational model is extended to support atomic and molecular semantics, which is a synthesis of many ideas from the published work in semantic modeling plus the introduction of new rules for insertion, update, and deletion.
Journal ArticleDOI
On the Desirability of Acyclic Database Schemes
TL;DR: It is shown that this class of database schemes, called acychc, has a number of desirable properties that have been studied by other researchers and are shown to be eqmvalent to acydicity.
Journal ArticleDOI
Query Optimization in Database Systems
Matthias Jarke,Jürgen Koch +1 more
TL;DR: These methods are presented in the framework of a general query evaluation procedure using the relational calculus representation of queries, and nonstandard query optimization issues such as higher level query evaluation, query optimization in distributed databases, and use of database machines are addressed.
Proceedings Article
Algorithms for acyclic database schemes
TL;DR: The purpose in this paper is to describe efficient algorithms in this setting for various problems, such as computing projections, minimizing joins, inferring dependencies, and testing for dependency satisfaction.
Journal ArticleDOI
Information systems theoretical foundations
TL;DR: The presented approach leads to a new information systems organization and the implementation shows many advantages compared with other methods.
References
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Book
The Design and Analysis of Computer Algorithms
Alfred V. Aho,John E. Hopcroft +1 more
TL;DR: This text introduces the basic data structures and programming techniques often used in efficient algorithms, and covers use of lists, push-down stacks, queues, trees, and graphs.
Journal ArticleDOI
Depth-First Search and Linear Graph Algorithms
TL;DR: The value of depth-first search or “backtracking” as a technique for solving problems is illustrated by two examples of an improved version of an algorithm for finding the strongly connected components of a directed graph.
Journal ArticleDOI
A relational model of data for large shared data banks
TL;DR: In this article, a model based on n-ary relations, a normal form for data base relations, and the concept of a universal data sublanguage are introduced, and certain operations on relations are discussed and applied to the problems of redundancy and consistency in the user's model.
Journal ArticleDOI
The design and implementation of INGRES
TL;DR: The currently operational (March 1976) version of the INGRES database management system is described in this article, which gives a relational view of data, supports two high level nonprocedural data sublanguages, and runs as a collection of user processes on top of the UNIX operating system for Digital Equipment Corporation PDP 11/40, 11/45, and 11/70 computers.
Proceedings Article
Dependency Structures of Data Base Relationships.
TL;DR: The results of the present paper are applied to derive new and simpler proofs of some theorems of Casey and Delobel [5] and some conclusions are given.