Verfahren zum Entfernen unbestätigter Änderungen an gespeicherten Daten durch ein Datenbankverwaltungssystem

摘要

A method of removing uncommitted changes made to stored data by a database management system, wherein the system stores a duplicate copy of data prior to effecting changes to the original copy, and upon failure of the system, or a transaction or transactions effecting the changes replaces the copy containing uncommited changes by the duplicate copy, characterised in that, in the case of failure of the system to replace the original copy (ie in the case of a backout failure), the system prevents subsequent attempts by the system to further change the data until the uncommitted changes have been removed by a process of backout failure processing, and wherein a batch backout utility program uses a set of system log records to bracket the duration of the backout failure for a particular file to track: whether the system completed its backout failure processing; which transactions had failed backout; and which transaction was the first to have a backout failure.