Optimizing chain queries in a distributed database system.
SIAM Journal on Computing
Query processing in a system for distributed databases (SDD-1)
ACM Transactions on Database Systems (TODS)
Tree queries: a simple class of relational queries
ACM Transactions on Database Systems (TODS)
Using Semi-Joins to Solve Relational Queries
Journal of the ACM (JACM)
A relational model of data for large shared data banks
Communications of the ACM
The Design and Analysis of Computer Algorithms
The Design and Analysis of Computer Algorithms
A methodology for interpreting tree queries into optimal semi-join expressions
SIGMOD '80 Proceedings of the 1980 ACM SIGMOD international conference on Management of data
Optimizing Star Queries in a Distributed Database System
VLDB '84 Proceedings of the 10th International Conference on Very Large Data Bases
The optimization of query processing on distributed database systems
The optimization of query processing on distributed database systems
Query Processing in Distributed Database System
IEEE Transactions on Software Engineering
Optimization Algorithms for Distributed Queries
IEEE Transactions on Software Engineering
Algorithms to Process Distributed Queries in Fast Local Networks
IEEE Transactions on Computers
| Hi-index | 14.98 |
The problem of optimal query processing in distributed database systems was shown to be NP-hard. This means that heuristic algorithms are necessary to solve the query processing problem. In this paper, we describe algorithms to improve the solutions generated by heuristics. We have identified four properties which optimal semijoin programs for processing tree queries have to satisfy. A semijoin program is represented by an execution graph which specifies the order and the identities of the semijoins to be executed. Given a semijoin program, we can therefore apply these properties to check its optimality. If it does not satisfy these optimality properties, the associated improvement algorithms can be applied to improve this program. No assumptions have been made about the relation size and the selectivity of the semijoins.