Abstract

A method of operating a computer system to store and retrieve information in a database uses a signature file of the database that is divided into subsets. A word signature is mapped to a particular subset during creation of the file and the same mapping information is used to retrieve the information in response to a query word. Each word signature is a logical word signature and has two components a physical word signature and a subset designation field. In this way, when information is retrieved from the database, only that subset containing the relevant word signature is scanned. The signature file is automatically created by the system as the database is stored on the data storage modules. During retrieval, the control reviews information received from the data storage means and if a match occurs between a physical word signature for a query word and a particular physical word signature arriving from the input section, the control sends the physical word signature to the FIFO buffer in memory together with the document identifier located subsequent to the matched physical word signature. The control then moves on to process the next physical word signature received from the data storage means. If there is no match, the control ignores the physical word signature and moves on to process the next physical word signature received from the data storage means. The control is effectively capable of processing several query words in parallel.