The article explores the design of relational databases specifically optimized for local SSDs, emphasizing the significant performance improvements these drives offer compared to traditional spinning disks. The author, an engineer at AWS, outlines four key approaches to modern database design that take advantage of these advancements. Notably, he references the five-minute rule for cache sizing, suggesting that databases should maintain caches for pages expected to be accessed within 30 seconds, a slight adjustment from the original rule established in 1986. Throughput and IOPS are also critical considerations. Modern SSDs perform best with transfers around 32kB, which balances throughput and IOPS. Transfers smaller than this can hinder performance, while larger ones offer diminishing returns. On the durability front, the article highlights the necessity of off-box replication to guard against data loss during failures. The network bandwidth of the i8g.48xlarge instance allows for synchronous replication, which poses a latency challenge, particularly when applications span multiple availability zones. Isolation in database transactions, particularly in a multi-AZ context, is another focus. The author contrasts two approaches: one that coordinates reads and writes at every transaction versus one that does so only at commit time. This decision impacts latency for applications relying on multiple AZs. Finally, the article critiques the traditional write-ahead log (WAL) model, arguing that it is less relevant for modern databases that can leverage replication across multiple systems for durability. The emphasis is on designing databases that capitalize on the powerful infrastructure of today's data centers while remaining responsive to the demands of contemporary applications.