On estimating block accesses in database organizations

In designing a physical database organization, one almost inevitably encounters the following estimating problem: Given k records to be retrieved oat of a f i le of n records organized into m blocks, how many of the m blocks have to be accessed? A correct solution to this problem was given by B. Yao. The solution as a function of Y(n, m, k) depends on the assumptions that n, m, and k are nonstochastic, as well as uniform block size. This paper examines the validity of this function when some of the assumptions are not true.