Reducing recovery constraints on locking based protocols

Abstract

Serializability is the standard correctness criterion for concurrency control. To ensure correctness in the presence of failures, recoverability is also imposed. Pragmatic considerations result in further constraints, for instance, the existing log-based recovery implementations that use before-images warrant that transaction executions be strict. Strict executions are restrictive, thus sacrificing concurrency and throughput. In this paper we identify the relation between the recovery mechanism and the restrictions imposed by concurrency control protocols. In particular, we propose a new inverse operation that can be integrated with the underlying recovery mechanisms. In order to establish the viability of our approach, we demonstrate the new implementation by making minor modifications to the conventional recovery architecture. This inverse operation is also designed to avoid the undesirable phenomenon of cascading aborts when transactions execute conflicting write operations.