Concurrency control theory for nested transactions

In this paper is presented a general model for nested transaction systems. The model is stated in abstract terms, and in addition to nesting it allows arbitrary transactions and operations. The model is very general so that results can be applied directly to a wide variety of applications. In particular, model can serve as a unified framework for dealing with concurrency in database systems. We have shown that the concept of commutativity can be extended by considering commutativity parameters. The treatment of synchronization mechanisms in database systems is oriented towards read/write operations, with read sets and write sets as arguments. Synchronization is often discussed in terms of the data items involved.