Recovery from information attacks is difficult because DBMS is not designed to deal with malicious committed transactions. A few existing methods developed for this purpose rely on operation logs, which can't express the dependency between different transactions directly. These methods usually use rollback mechanism and abandon results of innocent transactions to maintain correctness, which may indeed be used as an approach to realize DOS attack. Hence, it's necessary to find out the malicious transaction and subsequent transactions depending on it precisely. In this paper, the definition of transaction recovery log is presented and each log item records the actions taken in one transaction, by which, we can calculate transactions' dependency directly. Based on the log model and the algorithm for log's creation, the dependency calculation and data recovery algorithm are studied, which are proofed to be complete and correct. Using transaction recovery log and the algorithm, database system can significantly enhance the performance of recovery for defensive information warfare.
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