Code string processing system and method using intervals

Abstract

A data retrieval system which updates data quickly. A divider determines the first substring and second substring based on the code string from which a key string is retrieved. For each substring, a generator generates the dictionary data showing the correspondence between a trailing string, which is a trailing part of data in the substring, and the start position of the trailing string within the code string. A retriever a trailing string whose leading string is a key string or a part of the key string, based on the dictionary data. A remover removes duplicate trailing strings. When a changer changes the code string, an updater updates dictionary data associated with the substring based on the contents of the change. A first maintaining device maintains the boundary interval at a maximum key length or longer, and a second maintaining device maintains the boundary interval at a specified length or less.