On solving efficiently the view selection problem under bag and bag-set semantics ?
Query subexpressions do not always suffice for finding an optimal solution. Lgviews and subexpression views suffice for solving the bag version of the problem. d-Lgviews and subexpression views suffice for solving the bag-set version of the problem. Path-viewsets can be used to solve the bag version of the problem for path-queries. We prove significant conditions that useful viewsets satisfy under bag-set semantics.
view selection bag-set semantics query rewriting bag semantics