A generalized logout and recovery system for small CODASYL databases

Abstract

This paper describes an effective replacement for journaling to tape while updating a small CODASYL database, particularly in an online application.The journaling of before and after images of modified pages of the database is replaced with the logging of after images of modified records to a direct access file. To enable recreation of the database environment during recovery, all current database keys are logged with the record.Recovery of the database after system failure is accomplished by restoring the latest backup and reapplying all after images as recorded on the logout file.