DATA SECURITY SYSTEM FOR DATA BASE SYSTEM

摘要

PURPOSE:To use a physical file and the other index file as they are when the index file is abnormal by confirming a usable state by means of a using probability flag for a logical file and the index file, and then using the files. CONSTITUTION:A data base system has logical files 2-1,... 2-n, and an index file 3 in a physical file 1, and possesses several data blocks having various types of data records in the logical files 2-1,... 2-n and the index file 3. In control information 5-1,... 5-n and 7 in a control information storage part 6, which controls the chains of the data blocks of the logical file and the index file, the flags to indicate whether the files are usable is provided, and unusableness is set in the logical file and the index file in which abnormality is detected. The subsequent processing is executed with the use of the usable logical file and the index file.