Removing uncommitted changes made to stored data by a database management system

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 of a transaction or transactions effecting the changes, replaces the copy containing uncommitted changes by the duplicate copy. If the system fails to replace the original copy (as 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. Backout failure log records are created to track whether the system completed its backout failure processing (END), which transactions had failed backout (SUBSEQUENT), and which transaction was the first to have a backout failure (FIRST). A batch backout utility program uses the set of backout failure log records to bracket the duration of the backout failure for a particular file.