ICDT
2007
ACM
13 years 10 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...
DBPL
2007
Springer
13 years 10 months ago
2007
Springer
Abstract. The complexity of containment and satisfiability of conjunctive queries over finite, unranked, labeled trees is studied with respect to the axes Child, NextSibling, the...
SPIRE
2009
Springer
13 years 11 months ago
2009
Springer
Abstract. Term-partitioned indexes are generally inefficient for the evaluation of conjunctive queries, as they require the communication of long posting lists. On the other side, ...
ERSHOV
2009
Springer
13 years 11 months ago
2009
Springer
Abstract. We consider the problem of query containment for conjunctive queries with safe negation property. A necessary and sufficient condition for two queries to be in containmen...
STOC
2010
ACM
14 years 1 months ago
2010
ACM
EDBT
2008
ACM
14 years 4 months ago
2008
ACM
Data exchange is the problem of transforming data structured under a schema (called source) into data structured under a different schema (called target). The emphasis of data exc...
EDBT
2008
ACM
14 years 4 months ago
2008
ACM
In this paper we study the problem of mining all frequent queries in a given database table, a problem known to be intractable even for conjunctive queries. We restrict our attent...
EDBT
2006
ACM
14 years 4 months ago
2006
ACM
Scientific data in the life sciences is distributed over various independent multi-format databases and is constantly expanding. We discuss a scenario where a life science research...
EDBT
2004
ACM
14 years 4 months ago
2004
ACM
EDBT
2002
ACM
14 years 4 months ago
2002
ACM
The problem of finding contained rewritings of queries using views is of great importance in mediated data integration systems. In this paper, we first present a general approach f...