Paper Info
Title
Efficient evaluation of queries in a mediator for WebSources
Abstract
We consider an architecture of mediators and wrappers for Internet accessible WebSources of limited query capability. Each call to a source is a WebSource Implementation (WSI) and it is associated with both a capability and (a possibly dynamic) cost. The multiplicity of WSIs with varying costs and capabilities increases the complexity of a traditional optimizer that must assign WSIs for each remote relation in the query while generating an (optimal) plan. We present a two-phase Web Query Optimizer (WQO). In a pre-optimization phase, the WQO selects one or more WSIs for a pre-plan; a pre-plan represents a space of query evaluation plans (plans) based on this choice of WSIs. The WQO uses cost-based heuristics to evaluate the choice of WSI assignment in the pre-plan and to choose a good pre-plan. The WQO uses the pre-plan to drive the extended relational optimizer to obtain the best plan for a pre-plan. A prototype of the WQO has been developed. We compare the effectiveness of the WQO, i.e., its ability to efficiently search a large space of plans and obtain a low cost plan, in comparison to a traditional optimizer. We also validate the cost-based heuristics by experimental evaluation of queries in the noisy Internet environment.
Year
DOI
Venue
2002
10.1145/564691.564702
SIGMOD Conference
Keywords
Field
DocType
low cost plan,good pre-plan,query evaluation plan,wsi assignment,internet accessible websources,best plan,cost-based heuristics,limited query capability,extended relational optimizer,efficient evaluation,traditional optimizer,internet access,query optimization
Web search query,Data mining,Architecture,Computer science,Heuristics,Database,The Internet
Conference
ISBN
Citations 
PageRank 
1-58113-497-5
33
1.48
References 
Authors
32
5
Name
Order
Citations
PageRank
Vladimir Zadorozhny131045.33
Louiqa Raschid21522417.56
maria esther vidal378795.93
Tolga Urhan437144.86
Laura Bright517617.34