On estimating result sizes of multi-way spatial joins

Abstract

In a real life environment, spatial data is highly skewed. In general, there axe two kinds of skews in spatial data. One is the placement skew and the other is the area skew. This paper introduces methods and the characteristics of estimating the accurate result sizes of the multi-way join for the area skewed spatial data. Especially, this paper describes the number and sort of the statistics which the optimizer should keep in order to calculate the multi-way join result size. Experimental results show our approach generally provides accurate estimation for the multi-way join for the area skewed spatial data.