217 search results - page 15 / 44 » An optimization for query answering on ALC database |
SIGMOD
2002
ACM
14 years 7 months ago
2002
ACM
Relational query optimizers have traditionally relied upon table cardinalities when estimating the cost of the query plans they consider. While this approach has been and continue...
SIGMOD
2004
ACM
14 years 7 months ago
2004
ACM
We define a framework for static optimization of sliding window conjunctive queries over infinite streams. When computational resources are sufficient, we propose that the goal of...
ICDT
2009
ACM
14 years 8 months ago
2009
ACM
The class of unions of conjunctive queries (UCQ) has been shown to be particularly well-behaved for data exchange; its certain answers can be computed in polynomial time (in terms...
ICDT
1995
ACM
13 years 11 months ago
1995
ACM
A tuple t1 of relation R subsumes tuple t2 of R, with respect to a query Q if for every database, tuple t1 derives all, and possibly more, answers to query Q than derived by tuple ...
ICDE
2008
IEEE
14 years 8 months ago
2008
IEEE
This paper introduces U-relations, a succinct and purely relational representation system for uncertain databases. U-relations support attribute-level uncertainty using vertical pa...