Distributed databases principles and systems
Distributed databases principles and systems
Database machine performance: modeling methodologies and evaluation strategies
Implications of certain assumptions in database performance evauation
ACM Transactions on Database Systems (TODS)
Query processing in a system for distributed databases (SDD-1)
ACM Transactions on Database Systems (TODS)
Query optimization in star computer networks
ACM Transactions on Database Systems (TODS)
On estimating block accesses in database organizations
Communications of the ACM
Approximating block accesses in database organizations
Communications of the ACM
Access path selection in a relational database management system
SIGMOD '79 Proceedings of the 1979 ACM SIGMOD international conference on Management of data
Evaluation of the size of a query expressed in relational algebra
SIGMOD '81 Proceedings of the 1981 ACM SIGMOD international conference on Management of data
Estimating Block Accessses when Attributes are Correlated
VLDB '86 Proceedings of the 12th International Conference on Very Large Data Bases
VLDB '88 Proceedings of the 14th International Conference on Very Large Data Bases
On the development of a site selection optimizer for distributed and parallel database systems
CIKM '93 Proceedings of the second international conference on Information and knowledge management
Deciding to Correct Distributed Query Processing
IEEE Transactions on Knowledge and Data Engineering
IEEE Transactions on Knowledge and Data Engineering
A Method for Design and Performance Modeling of Client/Server Systems
IEEE Transactions on Software Engineering
A modeling tool for workload analysis and performance tuning of parallel database applications
ADBIS'97 Proceedings of the First East-European conference on Advances in Databases and Information systems
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The paper deals with the problem of evaluating how the originality of the attributes of a relation, i.e. the number of distinct values in each attribute, is affected by relational operations that reduce the cardinality of the relation. This is indeed an interesting problem in research areas such as database design and query optimization. Some authors have shown that non uniform distributions and stochastic dependence significantly affect the originality of the attributes. Therefore the models that have been proposed in the literature, based on uniformity and independence assumptions, in several situation can not be conveniently utilized. In this paper we propose a probabilistic model that overcomes the need of the uniformity and independence assumptions. The model is exact for non uniform distributions when the attributes are independent, and gives approximate results when stochastic dependence is considered. In the latter case the analytical results have been compared with a simulation, and proved to be quite accurate.