Dohyung Kim <dh2002(dot)kim(at)samsung(dot)com> writes:
> 1. why 3 daemon processes start in its starting point
> 2. what the roles of each 3 daemon processes are
Postmaster, statistics collector, and statistics buffer process.
> 3. and how can I control the initial number of daemon process.
You can't (other than by choosing to disable statistics collection,
in which case the two stats processes won't run).
regards, tom lane