两种限定误差直方图之对比

Comparion of Two Kinds of Errors of Limited Histogram

直方图是许多商用数据库系统中最常用的一种估算查询结果大小的方法．本文在作者已有研究基础上，对限定误差直方图方法进行了讨论，并对两种限定误差直方图方法作了实验对比．

Histogram is the conunonest method for she estimation of query result in many commercial database systems. In this paper, comparion two kinds of errors of limited histgram is made.