Search
Now showing items 1-5 of 5
-
Rewriting queries with arbitrary aggregation functions using views
(Association for Computing Machinery (ACM), 2006)The problem of rewriting aggregate queries using views is studied for conjunctive queries with arbitrary aggregation functions and built-in predicates. Two types of queries over views are introduced for rewriting aggregate ... -
Deciding equivalences among conjunctive aggregate queries
(Association for Computing Machinery, 2007)Equivalence of aggregate queries is investigated for the class of conjunctive queries with comparisons and the aggregate operators count, count-distinct, min, max, and sum. Essentially, this class contains unnested SQL ... -
Equivalences among Aggregate Queries with Negation
(Association for Computing Machinery (ACM), 2005)Query equivalence is investigated for disjunctive aggregate queries with negated subgoals, constants and comparisons. A full characterization of equivalence is given for the aggregation functions count, max, sum, prod, ... -
Stream Integration Techniques for Grid Monitoring
(Springer, 2005)Grids are distributed systems that provide access to computational resources in a transparent fashion. Providing information about the status of the Grid itself is called Grid monitoring. As an approach to this problem, ... -
Answering queries over incomplete data stream histories
(Emerald, 2007)Purpose – Distributed data streams are an important topic of current research. In such a setting, data values will be missed, e.g. due to network errors. This paper aims to allow this incompleteness to be detected and ...
