Query Evaluation on Probabilistic Databases
Christopher Ré, Nilesh N. Dalvi, Dan Mircea Suciu · IEEE Data(base) Engineering Bulletin · 2006
We describe a system that supports arbitrarily complex SQL queries with ”uncertain” predicates. The query semantics is based on a probabilistic model and the results are ranked, much like in Information Retrieval. Our main focus is query evaluation. We describe an optimization algorithm that can compute eciently most queries. We show, however, that the data complexity of some queries is #P-complete, which implies that these queries do not admit any ecient evaluation methods. For these queries we describe both an approximation algorithm and a Monte-Carlo simulation algorithm.