In this paper, we describe the Oracle Large User Population Demonstration and highlight the scalability mechanisms in the Oracle8 Universal Data Server which make it possible to support as many as 50,000 concurrent users on a single Oracle8 database without any middle-tier TP-monitor software. Supporting such large user populations requires many mechanisms for high concurrency and throughput. Algorithms in all areas of the server ranging from process and buffer management to SQL compilation and execution must be designed to be highly scalable. Efficient resource sharing mechanisms are required to prevent server-side resource requirements from growing unboundedly with the number of users. Parallel execution across multiple systems is necessary to allow user-population and throughput to scale beyond the restrictions of a single system. In addition to scalability, mechanisms for high availability, ease-of-use, and rich functionality are necessary for supporting complex user applications typical of realistic workloads. All mechanisms must be portable to a wide variety of installations ranging from desk-top systems to large scale enterprise servers and to a wide variety of operating systems.