Determining database record content changes

摘要

Database backup system identifies and extracts any changed database record using only two copies of the database from two different points in time. A first copy of the database is generated at a first time. Copies of log files including changes to the database since the first time are generated at a second time. The copy of the log files is applied to the database copy, and any changed blocks of the first copy of the database are identified. The changed blocks and a second copy of the database are used to identify changes to any record of the database between the first and second time. An archived database is generated and updated over time by archiving only data of any record that subsequently changes. Restoration of the database to a state corresponding to any point in time uses only the archived database and data of changed data records.