Patent ID: 7299248
Filing Date: 2007-11-20
Classification: G06F,Y10S

Abstract:
1. For a database management system to be operatively coupled to a data processing system, the data processing system comprising memory for storing a data table, a method of determining frequency of updating a histogram of the data table, the method comprising: determining sampled histograms for sample portions of the data table over a period of time; computing a difference between at least two of the determined sampled histograms; determining a frequency with which to update the histogram of the data table depending on the amount of the computed difference; and storing the determined frequency in the memory to update the histogram of the data table, wherein the determined sampled histograms include histogram sections; the step of computing the computed difference comprises: adjusting the sections of one sampled histogram to line up with sections of another sampled histogram; subtracting each section of the another sampled histogram from a corresponding section of the one sampled histogram; and computing the sum of the subtracted sections, wherein the method further comprises dividing the computed sum by a length of the x-axis of at least one of the one sampled histogram and the another sampled histogram.