On the optimal nesting order for computing N-relational joins
ACM Transactions on Database Systems (TODS)
Combinatorial optimization: algorithms and complexity
Combinatorial optimization: algorithms and complexity
Query optimization by simulated annealing
SIGMOD '87 Proceedings of the 1987 ACM SIGMOD international conference on Management of data
Principles of database and knowledge-base systems, Vol. I
Principles of database and knowledge-base systems, Vol. I
Optimization of large join queries
SIGMOD '88 Proceedings of the 1988 ACM SIGMOD international conference on Management of data
Optimization of large join queries: combining heuristics and combinatorial techniques
SIGMOD '89 Proceedings of the 1989 ACM SIGMOD international conference on Management of data
Randomized algorithms for optimizing large join queries
SIGMOD '90 Proceedings of the 1990 ACM SIGMOD international conference on Management of data
Access path selection in a relational database management system
Readings in database systems (2nd ed.)
Rapid bushy join-order optimization with Cartesian products
SIGMOD '96 Proceedings of the 1996 ACM SIGMOD international conference on Management of data
Template-based wrappers in the TSIMMIS system
SIGMOD '97 Proceedings of the 1997 ACM SIGMOD international conference on Management of data
On the complexity of generating optimal plans with cross products (extended abstract)
PODS '97 Proceedings of the sixteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Capability based mediation in TSIMMIS
SIGMOD '98 Proceedings of the 1998 ACM SIGMOD international conference on Management of data
The complexity of ordering subgoals
Proceedings of the seventh ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
An algorithm for ordering subgoals in NAIL?
Proceedings of the seventh ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Query processing in a system for distributed databases (SDD-1)
ACM Transactions on Database Systems (TODS)
Capabilities-based query rewriting in mediator systems
DIS '96 Proceedings of the fourth international conference on on Parallel and distributed information systems
Computers and Intractability: A Guide to the Theory of NP-Completeness
Computers and Intractability: A Guide to the Theory of NP-Completeness
On the Complexity of Generating Optimal Left-Deep Processing Trees with Cross Products
ICDT '95 Proceedings of the 5th 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 Nonrecursive Queries
VLDB '86 Proceedings of the 12th International Conference on Very Large Data Bases
Measuring the Complexity of Join Enumeration in Query Optimization
VLDB '90 Proceedings of the 16th International Conference on Very Large Data Bases
Fast, Randomized Join-Order Selection - Why Use Transformations?
VLDB '94 Proceedings of the 20th 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
The Complexity of Transformation-Based Join Enumeration
VLDB '97 Proceedings of the 23rd International Conference on Very Large Data Bases
Describing and Using Query Capabilities of Heterogeneous Sources
VLDB '97 Proceedings of the 23rd International Conference on Very Large Data Bases
Heuristic and randomized optimization for the join ordering problem
The VLDB Journal — The International Journal on Very Large Data Bases
Scaling heterogeneous databases and the design of Disco
ICDCS '96 Proceedings of the 16th International Conference on Distributed Computing Systems (ICDCS '96)
Analysis of distributed data base processing strategies
VLDB '80 Proceedings of the sixth international conference on Very Large Data Bases - Volume 6
Optimization Algorithms for Distributed Queries
IEEE Transactions on Software Engineering
On Answering Queries in the Presence of Limited Access Patterns
ICDT '01 Proceedings of the 8th International Conference on Database Theory
Answering Queries with Database Restrictions
SARA '02 Proceedings of the 4th International Symposium on Abstraction, Reformulation, and Approximation
Description Logics for Information Integration
Computational Logic: Logic Programming and Beyond, Essays in Honour of Robert A. Kowalski, Part II
Evolution of Query Optimization Methods: From Centralized Database Systems to Data Grid Systems
DEXA '09 Proceedings of the 20th International Conference on Database and Expert Systems Applications
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In data integration systems, queries posed to a mediator need to be translated into a sequence of queries to the underlying data sources. In a heterogeneous environment, with sources of diverse and limited query capabilities, not all the translations are feasible. In this paper, we study the problem of finding feasible and efficient query plans for mediator systems. We consider conjunctive queries on mediators and model the source capabilities through attribute-binding adornments. We use a simple cost model that focuses on the major costs in mediation systems, those involved with sending queries to sources and getting answers back. Under this metric, we develop two algorithms for source query sequencing - one based on a simple greedy strategy and another based on a partitioning scheme. The first algorithm produces optimal plans in some scenarios, and we show a linear bound on its worst case performance when it misses optimal plans. The second algorithm generates optimal plans in more scenarios, while having no bound on the margin by which it misses the optimal plans. We also report on the results of the experiments that study the performance of the two algorithms.