1 AIT Asian Institute of Technology

Concurrency control in distributed object-oriented databases

AuthorZhang, Wenhong
Call NumberAIT Thesis no.CS-93-22
Subject(s)Object-oriented databases

NoteA thesis submitted in partial fulfillment of the requirements for the degree of Master of Science
PublisherAsian Institute of Technology
AbstractA distributed object-oriented database system model is proposed. In this model, a collection of objects distributed over multiple nodes which are interconnected by a network. The network provides sharing of information between these nodes. The proposed model differs from the traditional models in a major aspect, which is the proposed model incorporates the concept of Abstract Data Type. That is, the database information is stored in typed objects ( i.e. instances of abstract data type) and manipulated only by operations that are specific to a particular object type. In this distributed object-oriented database system model, the distribution of data is invisible to users, users see the system as a single integrated database. Since users may issue transactions from their local sites, many transactions are allowed to be active simultaneously in the system. Therefore, a concurrency control scheme is required. Based on the proposed model, a type-specific multiversion timestamping concurrency control algorithm which is employed to synchronize transaction operations on shared objects is developed. We give a formal description of the algorithm, encompassing both concurrency control and recovery strategy, and prove that the algorithm satisfies ยท Static Atomicity, a Local Atomicity Propery that ensures global atomicity in distributed object-oriented database system. This algorithm has the following novel aspects. First, unlike many methods that classify operations only as reads and writes, this technique exploit the semantics of abstract data types to achieve greater concurrency. Synchronization is based on a predefined compatibility table. Second, this technique supports modular design. Global Atomicity of the system is achieved by satisfying properties that are local to individual objects. Third, this technique is more integrated, it analyzes serializability and recovery together, rather than treating them separately. A performance evaluation is carried out to compare the level of concurrency offered when we use the proposed concurrency control algorithm as opposed to using traditional scheme without exploiting semantic information. The evaluation result is that the proposed algorithm is suitable for distributed object-oriented databases and can achieve better concurrency.
Year1993
TypeThesis
SchoolSchool of Engineering and Technology (SET)
DepartmentDepartment of Information and Communications Technologies (DICT)
Academic Program/FoSComputer Science (CS)
Chairperson(s)Vilas Wuwongse;
Examination Committee(s)Yulu, Qi;Phan, Minh Dung;
Scholarship Donor(s)DAAD;
DegreeThesis (M.Sc.) - Asian Institute of Technology, 1993


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