Query optimization - The CROQUE project
This paper describes parts of a concept for the evaluation and optimization of ODMGOQL queries. We present a logical object algebra for the internal representation of OQL queries. Algebraic expressions are also represented as query trees. Different optimization techniques are sketched: factorization...
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| Format: | Text |
| Language: | English |
| Published: |
1996
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.31.3205 http://wwwdb.informatik.uni-rostock.de/~jo/rib_18_1995.ps.gz |
| Summary: | This paper describes parts of a concept for the evaluation and optimization of ODMGOQL queries. We present a logical object algebra for the internal representation of OQL queries. Algebraic expressions are also represented as query trees. Different optimization techniques are sketched: factorization of common subexpressions, dependency-based optimization and query rewriting. Afterwards, execution plan generation from query trees is presented. The transformation of physical queries into ObjectStore DML code and the developed cost model for the calculation of the costs of the execution plans are not considered here. Keywords: OQL, logical and physical algebra, optimization of object-oriented queries. 1 Introduction In the framework of the CROQUE project 1 we focus on the development of optimization techniques for object databases. Central topics of our work are examinations about rule-based rewriting of algebraic queries, cost-based selection of evaluation mechanisms for obje. |
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