Method for generating and searching a range-based index of word-locations

摘要

A method indexes a database so that records including literal values, and numeric values within a specified range can be located. The range is selected from an interval of values. Each record of the database is indexed by storing index entries in a memory. Each index entry includes a literal word entry representing a unique portion of information of the database, and one or more numeric location entries indicating occurrences of the portion of information. A plurality of sets of subintervals are generated from the numeric interval of values. Each set of subintervals includes all of the values of the interval. A first set includes one subinterval for each value of the interval, and each next set includes one interval for a group of adjacent subintervals of a previous set. The subinterval of the last set is the entire interval of numeric values. Each subinterval is represented by a unique literal which can be indexed as a word entry in the index. While indexing the records, some portions of information are identified as range-based values. The range-based values are indexed by storing word and location entries in the index such that there is one word entry for each subinterval which includes the range-based values, the locations indicating occurrences of the range-based portions of information.