On Detecting Conflict Between Proposed Updates

In the Heraclitus paradigm, a delta value or more simply, delta , is a concrete value that corresponds to a difference between database states. This paper presents the Heraclitus[OO] (abbreviated H2O) DBPL, which provides a syntax and semantics for working with deltas in the context of object-oriented databases. The paper also considers the use of deltas in connectionwith detecting conflict between pairs of proposed updates to a database. This is useful in contextswhere multiple users are each creating and choosing betweenmultiple possible updates. A semantically based notion of potential conflict between proposed updates is developed, along with several conservative approximations based on the use of different kinds of delta.