Log archive filtering method for transaction-consistent forward recovery from catastrophic media failures

摘要

A method for implementing transaction-consistent resource recovery from catastrophic media failures in a single pass over a recovery log archive while permitting most UNDO log records to be discarded during log archiving. The media recovery procedure is based on a pseudo-crash recovery technique that simulates a system crash at a selected time by writing PSEUDO-RECOVERY records to the recovery log. Resource recovery is then performed by normal execution of the log archive records up to the most recent pseudo-crash followed by execution of the subsequent PSEUDO-RECOVERY records. The recovery log record execution procedures are compatible with the ARIES recovery method. One embodiment of this invention assumes that the recovery log records can be selected for archiving on the basis of a combination of record type and transaction identifier.