Scheduling Distributed Real-Time Nested Transactions

Abstract

To ensure global serializability, traditional distributed database systems implement both concurrency control and transaction commit protocols. In a distributed database systems, a commit protocol guarantees the uniform commitment of distributed transaction execution. In the last decade, several extensions to the transaction model adopted in traditional database systems have been proposed in order to support the functional and performance requirements of emerging advanced applications such as CAD/CAM, large software design projects and object-oriented databases. Nested transaction models have been shown to play an important role in such applications, however, these models are not yet fully studied. In this paper, our contributions in the field of real-time nested transactions are two fold: (i) we propose a hierarchical and flat protocols for real-time nested transactions, called 2PC-RT-NT, and (ii) we implement a lock mechanism, called 2LP-NT-HP, to solve the data conflicts problem between nested transactions.

Priority-based speculative locking protocols for distributed real-time database systems.

“…Concurrency control mechanisms will be discussed further in the next section. [1,2]. This is due to the fact that these database applications are by nature long, complicated (in term of the complexity of operations involved in performing a transaction) and require access to data items at various network sites [1].…”

“…Several priority assignment policies are used for scheduling where the transaction that requires less work is given a higher priority [1]. Of these, the policy that assigns priority to a transaction based on its deadline has been broadly used [1,7] and has been found to be the best policy in terms of success ratio in most cases [2]. For a nested transaction, we have adopted the model that assigns subtransactions the same priority as their parent transaction.…”

“…Furthermore, to respond to the need of applications that rely on DRTDBS, a transaction model known as nested transaction has been widely adopted [1,2,3,4,5]. A nested transaction is considered as a hierarchy of subtransactions in which each subtransaction may contain other subtransactions, or contain atomic database operations (read or write) [4].…”