I often select PostgreSQL for my clients, generally strictly adhering to the relational paradigms and letting the web caching layer keeping out the performance

I often select PostgreSQL for my clients, generally strictly adhering to the relational paradigms and letting the web caching layer keeping out the performance problems. PostgreSQL installations I saw are almost never tuned, except few paramers like effective_cache_size and the use of a separate raid array for the transaction log. Scaling I saw is done vertically : faster hardware, more memory, SSD in raid 10. One of my clients tried once an horizontal scaling (with C-JDBC) but reverted back and bought a monster hardware.