METHODS FOR SPECIALLY DELETING AND RESTORING DATA COLUMN, PERMANENTLY AND RAPIDLY DELETING SPECIALLY DELETED DATA COLUMN, AND RECORDING MEDIUM FOR STORING ADDITIONAL INFORMATION FOR RESTORING COLUMN OR PERMANENTLY DELETING SPECIALLY DELETED DATA

摘要

PURPOSE: A method for specially deleting and restoring data column, permanently and rapidly deleting specially deleted data column, and recording medium for storing additional information for restoring column or permanently deleting specially deleted data are provided to store a searching information for restoring a specially deleted data column to an original state. CONSTITUTION: The method for specially deleting and restoring data column comprises the steps of: renewing only searching information for plural data columns which are created correspondingly to a sector to be specially deleted; and storing in the searching information a first additional information indicating that data column corresponding to the specially deleted sector is specially deleted, a second additional information indicating that a delectable sector exists upon performing a permanent deleting among data columns to which the first additional information is added, and a third additional information indicating a permanently delectable sector when the second additional information comes to effect.