A SAT approach to query optimization in mediator systems

11 years 5 months ago
A SAT approach to query optimization in mediator systems
Mediator systems integrate distributed, heterogeneous and autonomous data sources, but their e ective use requires the solution of hard query optimization problems. This is usually done in one of two ways: when the set of data sources is xed, their ordering into a feasible and e cient query is treated as a join order problem when the set is not known, their selection from a superset is treated as a set covering problem. This two-phase approach is unlikely to nd optimum queries, and we describe a generalised approach in which a feasible query is constructed from a subset of the available data sources. Under simple cost assumptions this can be encoded and solved as a SAT problem. Results on arti cial benchmarks indicate that this is an interesting problem, with a combination of features that make it hard for both complete and incomplete search. We investigate both types of algorithm and a hybrid approach, with and without symmetry breaking constraints. The best combination turns out to ...
Steven David Prestwich, Stéphane Bressan
Added 15 Dec 2010
Updated 15 Dec 2010
Type Journal
Year 2005
Where AMAI
Authors Steven David Prestwich, Stéphane Bressan
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