Optimization of multi-domain queries on the web
Proceedings of the VLDB Endowment
Assessing query privileges via safe and efficient permission composition
Proceedings of the 15th ACM conference on Computer and communications security
Satisfiability and relevance for queries over active documents
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Proceedings of the 13th International Conference on Extending Database Technology
Search computing: a model-driven perspective
ICMT'10 Proceedings of the Third international conference on Theory and practice of model transformations
Modeling search computing applications
ICWE'10 Proceedings of the 10th international conference on Current trends in web engineering
Determining relevance of accesses at runtime
Proceedings of the thirtieth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Cooperative data access in multi-cloud environments
DBSec'11 Proceedings of the 25th annual IFIP WG 11.3 conference on Data and applications security and privacy
Answering complex structured queries over the deep web
Proceedings of the 15th Symposium on International Database Engineering & Applications
Chapter 10: join methods and query optimization
Search Computing
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Data sources on the web are often accessible through web interfaces that present them as relational tables, but require certain attributes to be mandatorily selected, e.g., via a web form. In a scenario where we integrate a set of such sources, and we pose queries over them, the values needed to access a source may have to be retrieved from other sources that are possibly not even mentioned in the query: answering queries at best can then be done only with a potentially recursive query plan that gets all obtainable answers to the query. Since data sources are typically distributed over a network, a major cost indicator for the execution of a query plan is the number of accesses to remote sources. In this paper we present an optimization technique for conjunctive queries that produces a query plan that: (1) minimizes the number of accesses according to a strong notion of minimality; (2) excludes all sources that are not relevant for the query. We introduce Toorjah, a prototype system that answers queries posed on sources with limitations by means of optimized query plans. Toorjah adopts a strategy that is aimed to retrieve answers as early as possible during query processing, and to present them to the user as they are computed. We provide experimental evidence of the effectiveness of our optimization, by showing the reduction of the number of accesses in a large number of cases.