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Efficient optimization of a class of relational expressions (1979).
| Content Provider | CiteSeerX |
|---|---|
| Author | Aho, A. V. Sagiv, Y. Ullman, J. D. |
| Abstract | The design of several database query languages has been influenced by Codd’s relational algebra. This paper discusses the difficulty of optimizing queries based on the relational algebra operations select, project, and join. A matrix, called a tableau, is proposed as a useful device for representing the value of a query, and optimization of queries is couched in terms of finding a minimal tableau equivalent to a given one. Functional dependencies can be used to imply additional equivalences among tableaux. Although the optimization problem is NP-complete, a polynomial time algorithm exists to optimize tableaux that correspond to an important subclass of queries. |
| File Format | |
| Publisher Date | 1979-01-01 |
| Access Restriction | Open |
| Subject Keyword | Relational Expression Efficient Optimization Useful Device Important Subclass Minimal Tableau Equivalent Relational Algebra Polynomial Time Algorithm Exists Relational Algebra Operation Additional Equivalence Optimization Problem Functional Dependency Several Database Query |
| Content Type | Text |
| Resource Type | Article |
