Histogram method for size estimation of query result

The histogram is the most common method for size estimation of query results in many commercial database systems. Several histogram methods presented in the past have certain limitations in practicability due to their lack of guarantee of estimation accuracy. This paper presents two kinds of new histogram methods, which are easy to use and can guarantee the accuracy of the estimation. The influence of different data distributions on the histogram is discussed in the paper, and some important parameters of data distribution are introduced to help produce better histograms.