Patent ID: 7882114

Claim:
A data processing method for extracting a subset from tabular format data viewed as an array of records, each record including item values belonging to items, the method comprising the steps of: (a) constructing the tabular format data by creating information blocks corresponding to respective items, each information block including a first value list in which the item values are stored in order of item value numbers corresponding to the item values and a first pointer array in which pointer values indicating the item value numbers are stored in order of unique record numbers; (b) creating an ordered set array containing record numbers of records selected from the array of the records, wherein the selected record numbers are arranged in a specified order in the ordered set array; (c) comparing a size of the ordered set array with a size of the first value list, wherein, as a result of the comparison, when size of the ordered set array is smaller than the size of the first value list at a predetermined rate, then steps (d) and (e), are performed; (d) arranging a pointer value in the first pointer array at a position indicated by each of the record numbers of the ordered set array into an item value number array at a position corresponding to a position where the record number is arranged in the ordered set array; and (e) creating a second value list storing value elements contained in the item value number array and a second pointer array storing position elements indicating elements in the second value list corresponding to the record numbers by referring to the item value number array, wherein a value in the first value list is specified from a record number of the ordered set array through a first element in the second pointer array at a position indicated by the record number and a second element in the second value list at a position indicated by the first element in the second pointer array.