PostgreSQL is the closest to what you're looking for. It's really fast; if it doesn't meet your requirements you're probably already aware that you need a spec

PostgreSQL is the closest to what you're looking for. It's really fast; if it doesn't meet your requirements you're probably already aware that you need a specialized solution. Besides explicit indexing, it also analyzes your data and maintains stats that inform the query planner. As your tables grow and your schema evolves, it will change its query plans accordingly. It can be quite smart. (A few examples: it maintains histograms of common values, null percentages, correlation between physical ordering and logical ordering or rows, and much more). Of course, you also have a lot of flexibility to denormalize and get the best of both worlds.