Explore a robust simulation-based comparison of three major multiprocessor architectures—Shared Everything, Shared Nothing, and Shared Disks—for high-performance transaction processing. This whitepaper delves into concurrency control, lock management strategies, buffer consistency, and intra-query parallelism. With extensive experimental data, it provides practical insights for systems architects and database researchers aiming to build scalable and efficient transaction systems. It also introduces innovative SD architecture variations and measures their performance under real-world workloads.