Designing views to answer queries under set, bag, and bag-set semantics
Rada Y. Chirkova, Foto Afrati, Manolis Gergatsoulis, Vassia Pavlaki · NCSU Libraries Repository (North Carolina State University Libraries) · 2004
A lot of work has been done recently on optimizing queries in the presence of materialized views.However the majority of the research assumes set-theoretic semantics while SQL queries have bag-theoretic semantics (duplicates are not eliminated unless explicitly requested).This paper presents results on designing views to answer queries in relational databases under set, bag and bag-set semantics.The results can be used in finding sound and complete algorithms for designing views and rewriting queries under each of the three assumptions.