This paper proposes preservation as a new conflict relation in an object-based database. By explicitly including reverse-operations which bridge the gap between concurrency control and recovery, preservation can be used independently of execution contexts to which different recovery algorithms and/or object models give rise, and further it forms a basis for formulating semantics-based recovery. This paper also makes a t wo-dimensional( i.e., execution cent exts and operations' specifications)

more »

... mparison bet ween preservation and other conflict relations. Irr each execution cent ext, our formal comparison reveala that preservationbased concurrency control achieves more concurrency than commutativity-based one.