Abstract: A method of updating a database of records with an update database assigns fractional pseudo addresses to each of the update records. If an update database exists, the update records are first read within the range defined by a desired integer database address and the next greater integer address and those records are read preferentially over comparable records of the original database. Pseudo addresses associated with a delete address pointer serve the function of deleting records while duplications between the update pseudo addresses and the original physical addresses of the database allow changing of the records of original database.

Abstract: A central control apparatus and a plurality of terminal apparatuses are connected through a line. In the central control apparatus, a plurality of images are stored in an optical disk in accordance with a hierarchical structure having four hierarchical levels of cabinet, binder, document, and page, and retrieval information constituted by a plurality of keys each for retrieving a corresponding image is stored in a magnetic disk with different title structures (key structures) in units of binders. A desired image is retrieved from the optical disk in accordance with designation of the retrieval information stored in the magnetic disk. A metabinder having a plurality of binders having the same title structure of the retrieval information has a level higher than that of the cabinet. In the central control apparatus, a title table group of the metabinders is stored in the magnetic disk independently of the binders.