Journal ArticleDOI
Dynamic query evaluation plans
Goetz Graefe,K. Ward +1 more
- Vol. 18, Iss: 2, pp 358-366
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This work aims at developing criteria when re Optimization is required, how these criteria can be implemented efficiently, and how reoptimization can be avoided by using a new technique called dynamic query evaluation plans.Abstract:
In most database systems, a query embedded in a program written in a conventional programming language is optimized when the program is compiled. The query optimizer must make assumptions about the values of the program variables that appear as constants in the query, the resources that can be committed to query evaluation, and the data in the database. The optimality of the resulting query evaluation plan depends on the validity of these assumptions. If a query evaluation plan is used repeatedly over an extended period of time, it is important to determine when reoptimization is necessary. Our work aims at developing criteria when reoptimization is required, how these criteria can be implemented efficiently, and how reoptimization can be avoided by using a new technique called dynamic query evaluation plans. We experimentally demonstrate the need for dynamic plans and outline modifications to the EXODUS optimizer generator required for creating dynamic query evaluation plans.read more
Citations
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Journal ArticleDOI
Parallel database systems: the future of high performance database systems
David J. DeWitt,Jim Gray +1 more
Journal ArticleDOI
Query evaluation techniques for large databases
TL;DR: This survey describes a wide array of practical query evaluation techniques for both relational and postrelational database systems, including iterative execution of complex query evaluation plans, the duality of sort- and hash-based set-matching algorithms, types of parallel query execution and their implementation, and special operators for emerging database application domains.
Journal ArticleDOI
The state of the art in distributed query processing
TL;DR: The paper presents the “textbook” architecture for distributed query processing and a series of techniques that are particularly useful for distributed database systems, and discusses different kinds of distributed systems such as client-server, middleware (multitier), and heterogeneous database systems and shows how query processing works in these systems.
Proceedings ArticleDOI
CrowdDB: answering queries with crowdsourcing
TL;DR: The design of CrowdDB is described, a major change is that the traditional closed-world assumption for query processing does not hold for human input, and important avenues for future work in the development of crowdsourced query processing systems are outlined.
Proceedings ArticleDOI
An overview of query optimization in relational systems
TL;DR: The goal of this article is not to be comprehensive, but rather to explain the foundations and present samplings of significant work in this area of query optimization.
References
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TL;DR: Strategy for processing multivariable queries in the database management system INGRES is considered, and algorithms for reduction and for choosing the variable to be substituted are given.
Proceedings ArticleDOI
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