Methods for returning a corrupted database to a known, correct state

摘要

A corrupted database is returned to a correct state by rolling forward or backward through a change queue and applying changes to the database in a selective manner. Changes that did not cause the corruption are applied without modification when rolling forward or are skipped when rolling backward. Changes that caused corruption are addressed when rolling forward, such as by being ignored or modified and then applied. Changes that caused corruption are corrected when rolling backward.

主权项

1. A method of returning a corrupted database to a correct state, wherein a change queue is maintained that includes a plurality of changes made to the database, the plurality of changes including at least one change that corrupts the database, and one or more recovery points are maintained, at least one recovery point allowing for a copy of a correct database to be restored at the time of the recovery point, the method comprising:
(a) detecting corruption of the database; (b) providing an algorithm that detects changes to the database which potentially caused corruption of the database; (c) restoring a correct copy of the database from one of the recovery points; (d) rolling forward through the change queue from the recovery point of step (c) to the first change corrupting the database as determined by the algorithm in step (b) and applying some or all changes to the database up to the first corrupting change; and (e) rolling forward through the change queue from the first change corrupting the database as determined by the algorithm in step (b) and applying the changes to the copy of the database of step (c) in a selective manner, wherein the selective manner of applying the changes occurs by:
(i) examining each change using the algorithm to determine if the change caused corruption of the database,(ii) addressing any changes that caused corruption of the database, and(iii) applying without modification some or all changes that were determined not to have caused corruption of the database, wherein the corrupted database is returned to a correct state.