Validating Mediator Cost Models with DISCO
Hubert Naacke, Patrick
Valduriez, Anthony
Tomasic : Validating Mediator Cost Models with DISCO. Networking
and Information Systems Journal, 2(5-6), 1999
Abstract
DISCO is a mediator system developed at INRIA for accessing heterogeneous
data sources over the Internet. In DISCO, mediators accept queries from
users, process them with respect to wrappers, and return answers. Wrapper
provide access to underlying sources. To efficiently process queries, the
mediator performs cost-based query optimization. In a heterogeneous distributed
database, cost-estimate based query optimization is difficult to achieve
because the underlying data sources do not export cost information. DISCO's
approach relies on combining a generic cost model with specific cost information
exported by wrappers. In this paper, we validate DISCO's cost model based
on experimentation with real Web data sources. This validation shows the
efficiency of our generic cost model as well as the efficiency of more
specialized cost functions.