A Proof Procedure for Data Dependencies
Journal of the ACM (JACM)
PODS '87 Proceedings of the sixth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Answering queries using views (extended abstract)
PODS '95 Proceedings of the fourteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
InfoSleuth: agent-based semantic integration of information in open and dynamic environments
SIGMOD '97 Proceedings of the 1997 ACM SIGMOD international conference on Management of data
Answering recursive queries using views
PODS '97 Proceedings of the sixteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Complexity of answering queries using materialized views
PODS '98 Proceedings of the seventeenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
An adaptive query execution system for data integration
SIGMOD '99 Proceedings of the 1999 ACM SIGMOD international conference on Management of data
Generating efficient plans for queries using views
SIGMOD '01 Proceedings of the 2001 ACM SIGMOD international conference on Management of data
Principles of Database and Knowledge-Base Systems: Volume II: The New Technologies
Principles of Database and Knowledge-Base Systems: Volume II: The New Technologies
Database System Implementation
Database System Implementation
Access path selection in a relational database management system
SIGMOD '79 Proceedings of the 1979 ACM SIGMOD international conference on Management of data
Optimizing Queries with Materialized Views
ICDE '95 Proceedings of the Eleventh International Conference on Data Engineering
ICDE '96 Proceedings of the Twelfth International Conference on Data Engineering
Information Integration Using Logical Views
ICDT '97 Proceedings of the 6th International Conference on Database Theory
Optimizing Queries Across Diverse Data Sources
VLDB '97 Proceedings of the 23rd International Conference on Very Large Data Bases
Optimization of Run-time Management of Data Intensive Web-sites
VLDB '99 Proceedings of the 25th International Conference on Very Large Data Bases
A Scalable Algorithm for Answering Queries Using Views
VLDB '00 Proceedings of the 26th International Conference on Very Large Data Bases
Querying Heterogeneous Information Sources Using Source Descriptions
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
VLDB '97 Proceedings of the 23rd International Conference on Very Large Data Bases
Answering queries using views: A survey
The VLDB Journal — The International Journal on Very Large Data Bases
Optimal implementation of conjunctive queries in relational data bases
STOC '77 Proceedings of the ninth annual ACM symposium on Theory of computing
Object/relational query optimization with chase and backchase
Object/relational query optimization with chase and backchase
Query evaluation using overlapping views: completeness and efficiency
Proceedings of the 2006 ACM SIGMOD international conference on Management of data
On rewriting XPath queries using views
Proceedings of the 12th International Conference on Extending Database Technology: Advances in Database Technology
Computing certain answers in the presence of dependencies
Information Systems
Determinacy and query rewriting for conjunctive queries and views
Theoretical Computer Science
An expressive and efficient solution to the service selection problem
ISWC'10 Proceedings of the 9th international semantic web conference on The semantic web - Volume Part I
Rewriting conjunctive queries determined by views
MFCS'07 Proceedings of the 32nd international conference on Mathematical Foundations of Computer Science
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We study the problem of generating efficient, equivalent rewritings using views to compute the answer to a query. We take the closed-world assumption, in which views are materialized from base relations, rather than views describing sources in terms of abstract predicates, as is common when the open-world assumption is used. In the closed-world model, there can be an infinite number of different rewritings that compute the same answer, yet have quite different performance. Query optimizers take a logical plan (a rewriting of the query) as an input, and generate efficient physical plans to compute the answer. Thus our goal is to generate a small subset of the possible logical plans without missing an optimal physical plan. We first consider a cost model that counts the number of subgoals in a physical plan, and show a search space that is guaranteed to include an optimal rewriting, if the query has a rewriting in terms of the views. We also develop an efficient algorithm for finding rewritings with the minimum number of subgoals. We then consider a cost model that counts the sizes of intermediate relations of a physical plan, without dropping any attributes, and give a search space for finding optimal rewritings. Our final cost model allows attributes to be dropped in intermediate relations. We show that, by careful variable renaming, it is possible to do better than the standard ''supplementary relation'' approach, by dropping attributes that the latter approach would retain. Experiments show that our algorithm of generating optimal rewritings has good efficiency and scalability.