14248 search results - page 81 / 2850 » Queries |
DOLAP
2009
ACM
14 years 3 months ago
2009
ACM
In this paper, we investigate the problem of answering top-k queries via materialized views. We provide theoretical guarantees for the adequacy of a view to answer a top-k query, ...
ICDT
2007
ACM
14 years 3 months ago
2007
ACM
Abstract. We study containment of conjunctive queries that are evaluated over databases that may contain tuples with null values. We assume the semantics of SQL for single block qu...
SDMW
2007
Springer
14 years 3 months ago
2007
Springer
Abstract. We investigate the experimental effectiveness of query rewriting over XML security views. Our model consists of access control policies specified over DTDs with XPath e...
ICMCS
2006
IEEE
14 years 3 months ago
2006
IEEE
A visual query is based on pictorial representation of conceptual entities and operations. One of the most important features used in visual queries is the shape. Despite its intu...
TMRA
2005
Springer
14 years 2 months ago
2005
Springer
Abstract. This paper describes a query algebra for tolog, a query language for Topic Maps inspired by Prolog and very similar to Datalog. The language is based on binding variables...