> 2. Postgresql uses shared memory being process based architecture. Mysql uses
> process memory being threaded application. It does not need kernel settings to
> work and usually works best it can.
MySQL has other issues with the kernel due to their threading choice
such as memory limits per process, or poor threaded SMP support on some
platforms (inability for a single process to use more than one CPU at a
time regardless of thread count).
Threads aren't an easy way around kernel limitations, which is probably
why Apache has gone for a combination of the two -- but of course that
adds complexity.