Treffer: A Cost-Based Object Buffer Replacement Algorithm for Object-Oriented Database Systems

Many object-oriented database systems manage object buffers to provide fast access to objects. Traditional buffer replacement algorithms based on fixed-length pages simply assume that the cost incurred by operating a buffer is proportional to the number of buffer faults. However, this assumption no longer holds in an object buffer where objects are of variable-lengths and the cost of replacing an object varies for each object. In this paper, we propose a cost-based replacement algorithm for object buffers. The proposed algorithm replaces the objects that have minimum costs per unit time and unit space. The cost model extends the previous page-based one to include the replacement costs and the sizes of objects. The performance tests show that the proposed algorithm is almost always superior to the LRU-2 algorithm and in some cases is more than twice as fast. The idea of cost-based replacement can be applied to any buffer management architectures that adopt earlier algorithms. It is espe.