Extension of multi-version concurrency control mechanisms for long-duration transaction based on nested transaction model

In this paper, we have extended multi-version concurrency control mechanisms for long-duration transaction based on nested transaction model, and explained how both intra- and inter-transaction concurrency degree can be increased. Our method uses the concept of visible sets to allow a transaction to update an object updated by another uncommitted transaction, and defines dependency relationships between these transactions in order to guarantee consistency of databases.