TRANSACTIONS AND UPDATES IN DEDUCTIVE DATABASES

In this paper, we develop a new approach that provides a smooth integr ation of extensional updates and declarative query languages for deduc tive databases. The approach is based on a declarative specification o f updates in rule bodies. Updates are not executed as soon are evaluat ed. Instead, they are collected and then applied to the database when the query evaluation is completed. We call this approach nonimmediate update semantics. We provide a top-down and equivalent bottom-up seman tics which reflect the corresponding computation models. We also packa ge set of updates into transactions and we provide a formal semantics for transactions. Then, in order to handle complex transactions, we ex tend the transaction language with control constructors still preservi ng formal semantics and semantics equivalence.