A Study on Transaction Scheduling in Distributed Real-Time Database Systems

• Main Authors: Hong-Ren Chen, 陳鴻仁
• Other Authors: Y. H. Chin
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/60189547967791054074

博士 === 國立清華大學 === 資訊工程學系 === 91 === In recent years, a distributed real-time database system (RTDBS) has become increasingly important in many real-life applications such as Internet stocking trading system, telecommunication, aircraft tracking, and automated control of medical patient monitoring. It must not only satisfy the data consistency, but also consider the time constraints associated with a real-time transaction. In general, a remote transaction usually accesses some data located at remote sites. However, traditional real-time schedulers do not consider the impact of communication delay in transferring remote data, resulting in a high MissRatio for remote transactions. This dissertation proposes a new real-time scheduler called FHR to reduce the MissRatio and lessen the unnecessary waiting time due to communication delay for a remote transaction. Transactions in advanced real-time database applications are characterized by being long and complex. The traditional flat transaction model cannot support all the requirements of these advanced applications. Thus, nested transactions play an important role in such applications. Nowadays, most of real-time schedulers are developed on the base of flat transaction models. A new real-time scheduler for nested transaction models called FHRN is proposed to efficiently schedule real-time nested transactions in a distributed RTDBS. FHRN consists of (1) FHRNp policy to schedule real-time nested transactions, and (2) 2PL_HPN resolve the concurrent data-accessing problem among interleaved nested transactions.