RETRIEVAL SYSTEM FOR FREQUENTLY UPDATED DATA DISTRIBUTED ON NETWORK

A retrieval system for performing database retrieval in response to a retrieval request includes a database preparing means for collecting corresponding data to prepare a database under at least a condition that an update frequency range of data serving as a target for index table generation is uniquely assigned to the database, and an update frequency of data falls within the assigned update frequency range, or a mean update frequency of a data group to which the data belongs falls within the assigned update frequency range.