- Evaggelia PitouraAffiliated withUniversity of Ioannina
A query or execution plan for a query specifies precisely how the query is to be executed. Most often, the plan for a query is represented as a tree whose internal nodes are operators and its leaves correspond to the input relations of the query. The edges of the tree indicate the data flow among the operators. The query plan is executed by the query execution engine.
During query processing, an input query is transformed into an internal representation, most often, into a relational algebra expression. To specify how to evaluate a query precisely, each relational operator is then mapped to one or more physical operators, which provide several alternative implementations of relational operators.
A query plan for each query specifies the physical operators to be used for its execution and the order of their invocation. Most commonly, a query plan is rep ...
Reference Work Entry Metrics
- Query Plan
- Reference Work Title
- Encyclopedia of Database Systems
- p 2282
- Print ISBN
- Online ISBN
- Springer US
- Copyright Holder
- Springer Science+Business Media, LLC
- Additional Links
- Industry Sectors
- eBook Packages
- Editor Affiliations
- 1. College of Computing, Georgia Institute of Technology
- 2. Database Research Group David R. Cheriton School of Computer Science, University of Waterloo
- Author Affiliations
- 1. University of Ioannina, Ioannina, Greece
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