Document retrieval apparatus retrieving document data using calculated

Abstract

There is provided a document retrieval apparatus in which signatures can be easily extracted from document data, and false drop probability is reduced even for a long document so as to reduce a burden of eliminating the false drop. A processing unit converts the document data and the character string into character codes, respectively. The processing unit extracts signatures from each of the character codes, and calculates a record identifier of the document data to be stored based on a storing position of the document data in a record file. A data storing unit stores the document data to be registered in the record file, and stores the signature corresponding to the document data to be registered in a signature file. The signature is stored in a storing position in the signature file, the storing position being designated by the record identifier of corresponding document data stored in the record file. The processing unit retrieves the document data containing a character string identical to the character string to be searched for by referring to a record identifier calculated based on a storing position of the signature in a signature file.