Accurate and Efficient Inter-Transaction Dependency Tracking

A reparable database management system has the ability to automatically undo the set of transactions that are corrupted by a human error or malicious attack. The key technical challenge to building repairable database management systems is how to accurately and efficiently keep track of inter-transaction dependencies due to data sharing through a database or through an application. In this paper, we present the design, implementation and evaluation of the inter-transaction dependency tracking mechanisms used in a repairable database management system called Blastema, which adds fast repairability in a portable way to a commercial DBMS, Oracle 9.2.0. Compared with other repairable DBMSs, Blastema eliminates false positive dependencies using fine-grained inter-transaction dependency tracking, and is able to successfully recognize two major sources of false negative dependencies, phantom dependencies and dependencies among transactions due to application data sharing. With these advanced inter-transaction dependency tracking mechanisms, Blastema significantly improves the availability of modern DBMSs by facilitating and sometimes even automating the damage repair process after a human error or a malicious attack. Performance measurements on a fully operational Blastema prototype run under the TPC-C benchmark show that the average run-time throughput penalty of the proposed inter-transaction dependency tracking mechanisms is less than 18%.