EDRC

Advancing the distributed real-time database systems (DRTDBS) performance requires critical consideration of the reasons for data inaccessibility (i.e., predictability and consistency, scheduling and conflict resolution schemes, and commit process). Traditionally, execute-commit conflict is handled through the two-phase commit protocol to ensure the consistency of the database by blocking an incoming cohort intending to access the data item(s) already locked by other prepared cohort. Such blocking makes the transaction execution time of incoming cohort unpredictable due to unbounded waiting time. This chapter proposes an early data lending-based real-time commit (EDRC) protocol that increases data accessibility by providing the means to start the lending process early. Furthermore, lender is permitted to lend its uncommitted data items just after the completion of data processing task. The EDRC protocol outperforms state-of-the-art distributed commit protocols particularly PROMPT, 2SC, and SWIFT under all load conditions.

Transaction Scheduling Heuristics in Mobile Distributed Real Time Database System

Background: Today's widely used small and portable mobile database technologies have geared toward the mobile distributed real-time database systems (MDRTDBS).Various real time applications like mobile devices, missile systems, navigation control systems, satellites and many others are some examples of MDRTDBS. In the new era of technology, a large domain of applications are based on MDRTDBS, meanwhile different intrinsic limitation like disconnection and mobility typically effect on its correct execution. Mobile distributed real-time systems have different wireless constrained such like energy, processing capacity, memory storage facilities and variable network communication channels. In last few years, different applications run on different mobile nodes needed a suitable transaction mechanism to complete their service without failing its deadline. In recent years researchers focused on MDRTDBS, to develop a suitable concurrency control, commit control method. Replication, check pointing, security, caching and query processing are some other hot research topics in the field of MDRTDBS. Objective: it is needed to maintain data consistency and correct results in mobile distributed real time database system. In our review we have identified key issues which might be considered for development of various transaction executing protocols. We have Introduce a taxonomy of different CC, commit, replication and security issues, which could be advantageous for design, and development of transaction protocols. Method: In the review we have discussed various concurrency, commit, replication methods. Apart from these we have discussed various check pointing, caching and query techniques which is developed in database system. A comparison among various concurrency and commit protocols has been done in the review. The role of different key methods which can affect and help the transaction execution in wireless environment is discussed separately in the paper. Results: Analytical results are not mentioned in the review paper. However the role and affect on the transaction execution are mentioned clearly. Issues and their advantages of different concurrency and commit protocols are mentioned. Results: Analytical results are not mentioned in the review paper. However the role and affect on the transaction execution are mentioned clearly. Issues and their advantages of different concurrency and commit protocols are mentioned. Conclusion: It is found that transaction processing is still a challenging area of research. A number of issues has been discussed and reviewed various approaches to control concurrency control and atomicity methods. We have presented a detailed survey and classification of various issues based on commit, concurrency, and replication methods for MTDRTDBS. However, in the paper different security, caching and query processing and check pointing issues has been also discussed which should be considered for future work. Database researchers have needed to integrate these issues with their work and develop a suitable protocol.

A Survey on Efficient Concurrency Control Algorithm in Distributed Database Systems

Transaction commit protocols help in reaching an agreement among the participating nodes when a transaction has to be committed or aborted. To initiate an agreement each participating node is asked to vote its decision on the operations on its transactional fragment. The participating nodes can decide to either commit or abort an ongoing transaction. In case of a node failure, the active participants take essential steps such as running the termination protocol to preserve database correctness. This paper sought to investigate the current distributed databases commit protocols such as 2PC and 3PC in order to pin-point their shortcomings. For instance, 2PC suffers from blocking of participant site in case of coordinator failure and increased latency due to forced writes of logs. On its part, 3PC suffers more communication overhead due to extra pre-commit phase. Based on these setbacks, an efficient protocol is suggested towards the end of this paper that it believed to address some of the challenges such as blocking and extra message exchange between communicating nodes.

A Context-Driven Commit Protocol for Enhancing Transactional Services Performance in Pervasive Environments

The proposed techniques for wireless environments during the last decade have limited support for dynamically changing environments. Due to its nature, the mobile computing environment is extremely dynamic and subject to rapid and unpredictable changes. Similarly, the characteristics of mobile applications affect their transactional requirements. The challenge is to reflect on solutions offering more flexibility and adaptability. In this article, the contribution was focused mainly on the problem of atomic commit that ensures the atomicity property. The trail of adapting mobile transaction commit protocols to context changes has been explored. This has led to the formalization of a flexible transaction model CATSM that supports adaptable properties and a commit protocol CA-TCP that enables adaptation to application requirements and mobile context in terms of transactional properties and execution cost. An architecture based on the concept of adaptation policy has also been designed for the implementation of the proposed solution.