Estimating Block Accesses when Attributes are Correlated (1986)
| Citations: | 2 - 0 self |
BibTeX
@MISC{Zanden86estimatingblock,
author = {Brad T. Vander Zanden and Howard M. Taylor and Dina Etitton},
title = {Estimating Block Accesses when Attributes are Correlated},
year = {1986}
}
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Abstract
database systems fallaciously assume that attributes are independent. This assumption leads such systems to systematically overestimate’the costs of queries and thus to select execution strategies that substantially increase the que.ries ’ processing time. In this paper we show how the concepts of Schur concavity and majorizahon can be used to elficiently estimate.the cost of a query when the queried attribute is correlated with the clustering attribute. We will also examine how a block access distribution can be constructed when attributes are correlated in this manner.
