Coping with Incomplete Data: Recent Advances

摘要: Handling incomplete data in a correct manner is notoriously hard problem databases. Theoretical approaches rely on the computationally notion of certain answers, while practical solutions ad hoc query evaluation techniques based three-valued logic. Can we find middle ground, and produce answers efficiently?The paper surveys results last few years motivated by this question. We re-examine certainty itself, show that it much more varied than previously thought. identify cases when can be computed efficiently and, short that, provide deterministic probabilistic approximation schemes for them. look at role logic as used SQL evaluation, discuss correctness choice, well necessity such producing answers.