2978	 Analysis of Design Alternatives for Virtual Memory Indexes	 A class of index structures for use in a virtual memory environment is described. Design alternatives within this class of index structures are analyzed. These alternatives include a choice of search strategy whether or not pages in the index are structured and whether or not keys are compressed. The average cost of retrieving entries from these indexes is expressed as a wieghted sum of the cost of a basic key comparison and the cost of crossing a page boundary in the index structure. Formulas for the retrieval costs for possible combinations of design alternatives are given. These are used in numerical case studies which compare the retrieval costs of the alternatives. Qualitative comparisons of the main tenance costs insertion deletion reorganization of the design alternatives are also included. index index structure pages virtual memory files retrieval main tenance search strategy key compression
