While modern hardware keeps offering increased parallelism and capabilities, harnessing them has been a perpetual challenge for decades for data-intensive systems. In particular, hardware trends oblige software to overcome three major challenges against systems scalability: (1) Taking advantage of the implicit parallelism within a core, (2) Exploiting the abundant explicit parallelism provided by multicores, (3) Achieving predictably efficient execution despite the non-uniform access latencies in multisocket multicores. This lecture will focus on these challenges in the context of transaction processing systems.