DATA PROCESSING APPARATUS AND METHOD

A data processing apparatus for extracting, from a set of data having a vector format stored in a database, a first prescribed number of items of data having a high degree of similarity with a query vector includes a list creation unit and a candidate output unit. The list creation unit creates lists of data in each of which data of the database is sorted in order of decreasing strength of respective one component of a vector. The candidate output unit decides the priority of each list, successively selects, from the lists based upon the list priority and ranking in each list, a second prescribed number of items of data not yet output, and outputs one item of data, from the second prescribed number of items of data selected, based upon degree of similarity between each item of the above-mentioned data and the query data. By virtue of the list creation unit and candidate output unit, the first prescribed number of items of candidate data similar to a query vector are obtained at high speed from the data in the database.