Dynamic Replication based Real Time Distributed Database: Issues and Challenges
Efficient replication protocols are required to satisfy the stringent requirement of mutual consistency and timeliness for replicated distributed real-time database system (RDRTDBS). Existing protocol such as distributed two-phase locking (D2PL) is well suited for providing strict correctness but suffers from long blocking delays, priority inversion, deadlock and lack of consideration of timing constraint. These issues cause many real-time transactions (RTTs) to miss their deadline. The main goal is to improve transaction miss ratio (TMR) for admitted RTTs. This paper proposes the concept of the dynamic version of the data object which will create the multiple versions of the data object as per admitted RTTs and finally converge to a single value following one copy serializability (1SR) correctness criteria. Additionally, it is also proposed to broadcast the admitted RTT during the locking phase of D2PL, so that, decentralized decision for commit or abort can be taken independently. The proposed concept of the dynamic version of the data object performs better as compared to existing concepts of dual version or multi-version data object.
Keywords - RDRTDBS; Replication Protocol; RTT; Dynamic Version Data Object; 1SR.