141 search results - page 1 / 29 » Equivalence of queries combining set and bag-set semantics |
PODS
2006
ACM
14 years 5 months ago
2006
ACM
The query equivalence problem has been studied extensively for set-semantics and, more recently, for bag-set semantics. However, SQL queries often combine set and bag-set semantic...
ICDT
2012
ACM
11 years 7 months ago
2012
ACM
The problems of query containment, equivalence, and minimization are recognized as very important in the context of query processing, specifically of query optimization. In their...
PODS
2009
ACM
14 years 5 months ago
2009
ACM
We consider the problem of deciding query equivalence for a conjunctive language in which queries output complex objects composed from a mixture of nested, unordered collection ty...
DBPL
1993
Springer
13 years 9 months ago
1993
Springer
In this paper we study the expressive power of query languages for nested bags. We de ne the ambient bag language by generalizing the constructs of the relational language of Brea...
AMW
2011
12 years 8 months ago
2011
Abstract. We consider the problem of checking equivalence of conjunctive queries with inequalities under bag (multiset) semantics. The problem is known to be decidable in pspace an...